4 light years travel time

Light Year Calculator

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With this light year calculator, we aim to help you calculate the distance that light can travel in a certain amount of time . You can also check out our speed of light calculator to understand more about this topic.

We have written this article to help you understand what a light year is and how to calculate a light year using the light year formula . We will also demonstrate some examples to help you understand the light year calculation.

What is light year?

A light year is a unit of measurement used in astronomy to describe the distance that light travels in one year . Since light travels at a speed of approximately 186,282 miles per second (299,792,458 meters per second), a light year is a significant distance — about 5.88 trillion miles (9.46 trillion km) . Please check out our distance calculator to understand more about this topic.

The concept of a light year is important for understanding the distances involved in space exploration. Since the universe is so vast, it's often difficult to conceptualize the distances involved in astronomical measurements. However, by using a light year as a unit of measurement, scientists and astronomers can more easily compare distances between objects in space.

How to calculate light years?

As the light year is a unit of measure for the distance light can travel in a year , this concept can help us to calculate the distance that light can travel in a certain time period. Hence, let's have a look at the following example:

• Source: Light
• Speed of light: 299,792,458 m/s
• Time traveled: 2 years

You can perform the calculation in three steps:

Determine the speed of light.

The speed of light is the fastest speed in the universe, and it is always a constant in a vacuum. Hence, the speed of light is 299,792,458 m/s , which is 9.46×10¹² km/year .

Compute the time that the light has traveled.

The subsequent stage involves determining the duration of time taken by the light to travel. Since we are interested in light years, we will be measuring the time in years.

To facilitate this calculation, you may use our time lapse calculator . In this specific scenario, the light has traveled for a duration of 2 years.

Calculate the distance that the light has traveled.

The final step is to calculate the total distance that the light has traveled within the time . You can calculate this answer using the speed of light formula:

distance = speed of light × time

Thus, the distance that the light can travel in 100 seconds is 9.46×10¹² km/year × 2 years = 1.892×10¹³ km

How do I calculate the distance that light travels?

You can calculate the distance light travels in three steps:

Determine the light speed .

Determine the time the light has traveled.

Apply the light year formula :

distance = light speed × time

How far light can travel in 1 second?

The light can travel 186,282 miles, or 299,792,458 meters, in 1 second . That means light can go around the Earth just over 7 times in 1 second.

Why is the concept of a light year important in astronomy?

The concept of a light year is important in astronomy because it helps scientists and astronomers more easily compare distances between objects in space and understand the vastness of the universe .

Can light years be used to measure time?

No , despite the name, you cannot use light years to measure time. They only measure distance .

Speed of light

How Long Would It Take To Travel A Light Year

Using the fastest man-made vehicle, NASA’s Juno spacecraft, which travels at 165,000 mph (365,000 kmph), it would take 2,958 years to travel a light year. A light year is equivalent to about 5.88 trillion miles (9.46 trillion kilometers).

Traveling at the speed of light would be the fastest way to cover vast distances in space, but current technology makes it impossible for humans or even our most advanced spacecraft to reach this speed.

Can people match the speed of a light year?

According to Einstein, it is impossible to match the speed of light. It is because light is the fastest thing in the universe, traveling at 186,000 miles per second (300,000 kilometers per second). There is not one thing that we could invent that could even match a fraction of how fast light travels.

Some scientists have theorized that a new type of engine, called a warp drive , could potentially allow humans to reach the speed of travel required to match the speed of light. However, even if future spacecrafts were able to achieve this level of propulsion, it would still take thousands of years to travel from one star system to another.

Despite the challenges, scientists continue to study space travel at faster-than-light speeds, as they are optimistic that one day we will be able to explore the vast reaches of our universe and even discover life on other planets.

For now, it would take many thousands of years to travel a light year using current technology. However, scientists remain hopeful that one day we will be able to explore the far reaches of space and perhaps even discover other life forms in distant star systems. Until then, we can continue marveling at the

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Can We Really Get to Alpha Centauri?

In a previous episode, I said that traveling within the Solar System is hard enough, traveling to another star system in our lifetime is downright impossible. Many of you said it was the most depressing episode I’ve ever done .

The distance to Pluto is, on average, about 40 astronomical units. That’s 40 times the distance from the Sun to the Earth. And New Horizons, the fastest spacecraft traveling in the Solar System took about 10 years to make the journey.

The distance to Alpha Centauri is about 277,000 astronomical units away (or 4.4 light-years). That’s about 7,000 times further than Pluto. New Horizons could make the journey, if you were willing to wait about 70,000 years. That’s about twice as long as you’d be willing to wait for Half Life 3.

But my video clearly made an impact on a plucky team of rocket scientists, entrepreneurs and physicists, who have no room in their personal dictionary for the word “impossible”. Challenge accepted, they said to themselves.

In early April, 2016, just 8 months after I said it was probably never going to happen, the billionaire Yuri Milner and famed physicist Stephen Hawking announced a strategy to send a spacecraft to another star within our lifetime. In your face Fraser, they said… in your face.

The project will be called Breakthrough Starshot, and it’s led by Pete Worden, the former director of NASA’s AMES Research Center – the people working on a warp drive.

The team announced that they’re spending $100 million to investigate the technology it’ll take to send a spacecraft to Alpha Centauri, making the trip in just 20 years. And by doing so, they might just revolutionize the way spacecraft travel around our own Solar System.

So, what’s the plan? According to their announcement, the team is planning to create teeny tiny lightsail spacecraft, and accelerate them to 20% the speed of light using lasers. Yes, everything’s made better with lasers .

We’ve talked about solar sails in the past, but the gist is that photons of light can impart momentum when they bounce off something. It’s not very much, but if you add a tremendous amount of photons, the impact can be significant. And because those photons are going the speed of light, the maximum speed for the spacecraft, in theory, is just shy of the speed of light (thanks relativity).

You can get those photons from the Sun, but you can also get them from a directed laser beam, designed to fill the sails with photons, without actually melting the spacecraft.

In the past, engineers have talked about solar sails that might be thousands of kilometers across, made of gossamer sheets of reflective fabric. Got that massive, complicated sail in your mind?

Now think smaller. The Starshot spacecraft will measure just a few meters across, with a thickness of just a few atoms. The sail would then pull a microscopic payload of instruments. A tiny chip, capable of gathering data and transmitting information – these are called Starchips. Not even enough room for water bear crew quarters.

With such a low mass, a powerful laser should be able to accelerate them to 20% the speed of light, almost instantly, making a trip to Alpha Centauri only take about 20 years.

Since each Starshot might only cost a few dollars to make, the company could manufacture thousands and thousands, place them into orbit, and then start bugzapping them off to different stars.

There are, of course, some massive engineering hurdles to overcome.

The first is the density of the interstellar medium. Although it’s almost completely empty in between the stars, there are the occasional dust particles. Normally harmless, the Starshots would be smashing into them at 20% the speed of light, which would be catastrophic.

The second problem is that this is a one-way trip. Once it’s going 20% the speed of light, there’s no way to slow the spacecraft down again (unless the Alpha Centaurans have a braking system in place). Just imagine the motion blur and targeting problems when you’re trying to take photos at relativistic speeds.

The third problem, and this is a big one, is that the miniaturization of the spacecraft means that you can’t have a big transmitter. Communicating across the light years takes a LOT of power. Maybe they’ll connect up into some kind of array and share the power requirement, or use lasers to communicate back. Maybe they’ll relay the data back like a Voltron daisy chain.

Even though the idea of traveling to another star might seem overly ambitious today, this technology actually makes a lot of sense for exploration in our own Solar System. We could bugzap little spacecraft to Venus, Mars, the outer planets and their moons – even deep into the Kuiper Belt and the totally unexplored Oort cloud. We could have this whole Solar System on exploration lockdown in just a few decades.

Even if a mission to Alpha Centauri is currently science fiction, this miniaturization is going to be the way we learn more about the Solar System we live in. Let’s get going!

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37 Replies to “Can We Really Get to Alpha Centauri?”

You are missing one huge problem. The military-political problem. That laser array would be a weapon that could clear near space of any and all satellites. I doubt that the major powers would stand by and allow it to be built. The obvious solution would be to build it on the lunar farside out of line-of-sight view of earth orbit. But that would add a whole new complexity to the project.

“NASA’s AMES Research Center – the people working on a warp drive.”

Two things:

1) It’s “Ames”, not “AMES”. The center is named after Joseph Sweetman Ames, it’s not an acronym.

2) NASA is not and has never been working on a warp drive, not at Ames, or any of the other centers.

Of course we can get there. I go all the time. Why don’t you ask something meaningful like, “When are they finally going to fix that leak in the men’s room of the McDonald’s on Fleeptor Street on Arglax 7 in the Gamma Quadrant?” — Miss Thorb, substitute 4th grade teacher from Mars, currently on assignment in Topeka. (To see aliens jump off the page of her new book and walk around your desk, visit: OurTeacherIsACreature.com)

Before we go nuts sending chip-sized spacecraft all over the solar system, lets send a few out to Mars and see how effective they are at acquiring data and sending it back to Earth.

in my heart i have felt the pain of wanting to fly and never die! but in my mind i have been there a thousand times.

The speed of light is approximately 700 million miles per hour. 20% is approximately 140 million mph. It doesn’t seem like we will be doing manned intersteller space travel anytime soon. WARP speed acceleration would squish the human body like a bug hitting a windshield.

Accelerating at 1G, it would take about a year to reach 99% the speed of light. We all experience 1G living on the Earth’s surface. There would be no difference physically

Also someone had a report recently about a large boundary layer for each galaxy with extremely high temperatures and great breadth. Don’t plan on visiting Andromeda points anytime soon.

Here are some numbers for you. A spaceship leaving Earth under a constant acceleration of Earth gravity (32 feet per second squared) would require about one year to reach the orbit of Pluto, and would then be traveling at approximately the speed of light.

At this velocity how long would it take to travel to Uranus?

Approx. 813.45 minutes plus any acceleration time.

After buying my new car, I was planning to drive to Alpha Centauri by myself, since I’ve never been there, however, before doing so, I checked with my auto insurer, AAA, for additional maps, and such, but, regrettably, I was informed they do not have any facilities there, and as such, they would not would not extend my coverage to that local. Thus, I’ll have to change my itinerary and settle for the Grand Canyon or someplace less distant.

I’ve been there before, and I can tell you, in no uncertain terms, Alpha Centauri is an inhospitable destination for anyone wishing a warm vacation. It’s way too cold for me and the wife. As such, next vacay we’ll just plan on staying in our own Solar System. Plus, my AAA car insurance will not cover us outside our Solar System.

Solar Sails and laser beams, to infinity and beyond. Give me a break. This is nonsense that is trotted out by a branch of science that is 1) eager for funding so their jobs can go on and they can retire well; 2) these same are outside of the loop for black-ops that are ultra secret, so much so that Congress is not reported to. Those lads are working on the real propulsion systems to get us out of the solar system. And no, you cannot send a news crew to any of their locations and ask for an interview. That doesn’t mean that evidence is missing. Just harder to isolate.

Where are Capt. Kirk, Scotty, and all those guys?

Don’t forget the aliens will come…

Don’t forget the aliens will come

Are there diamonds there like in Saturn’s rings?

Can you get to the mars? isn’t a priority?

The concept of faster space travel is certainly intriguing but as you state, the speed of light is the ultimate finality unless things like wormholes prove to be what we would like them to be. Moving around the universe at a percentage of the speed of light makes interstellar travel very, very long term and difficult. What we ignore is that if it is that difficult for us, it is just as difficult for the “aliens” out there. The distances are immense and until the finality becomes just another speed bump, it is highly unlikely that we will meet an alien anytime soon.

The obvious way to slow the spacecraft down is turn the light sail around and use it as a parachute. The interstellar medium does indeed have enough particles to slow the spacecraft to controllable speeds; likewise the parachute will absorb enough energy for radio transmission power.

What bothers me is the control system needed to maintain focus on the sail during acceleration and second, can we really build a perfectly reflective light sail.

Nevertheless a fascinating possibility which I hope there are people available who can make it happen. I would certainly donate to the effort.

If we cannot come out with far more advance propulsion system and fuel, we will not go far. Also we need to think about what we define about habitual planet. Life will develop and advance according to that particular planet. It is passible aliens doesn’t breath on oxygen and need liquid water, but other air and liquid to survived. It is also possible they need lighter or heavier gravity. Aliens may also develop far more advance communicate technologies than what we develop on Earth.

This subject again. I get tired of going through the “accelerate for 388 days at 1G to the speed of light then face the other way decelerate for 388 days back to stop”…. speil…. With the magical drive system that hasn’t been invented yet…. I think you’d only be half way across. You’d have to go 5 or 600 days of 1G acceleration and then 5 0r 600 days of same deceleration. You wouldn’t vaporize or go back in time. They used to think that about breaking the sound barrier too.

Why not just have a set of orbital solar concentrators focusing the sun’s output ’round the clock, “bugzapping” (as you call it) the little fellas without the atmosphere and rotation of the earth to worry about? And it’s fairly arrogant to claim that Milner and Hawking read your article and said, “Gee, I never thought about any of this until Fraser Cain dreamt it up; I’d better get cracking!”

You want the light finely-tuned to a wavelength that isn’t absorbed by the sail; only lasers can provide that. But it wouldn’t work anyway. Flying through the Local Bubble, there are enough dust grains to destroy even a Whipple shield equipped sail in a matter of hours. At 60,000 km/s, a 1 meter sail would hit dozens of grains of dust per second; most of them only a few molecules in size, but something like one seriously big (100 nanometers) every minute, that would put a healthy sized hole in the forward shield. In one hour it would be in tatters, and in a few months, even the payload would be seriously eroded.

AJ’s rule: If UFO’s are real, then interstellar travel is ridiculously easy (we just havn’t found out how yet). If it’s not easy, then the energy/time needed would be daunting for a type 4 civilization. Especially considering we are just one more unremarkable piece of real estate not worth visiting. It’s just our hubris that we are special when it’s clear we are not the center of the universe or anything else. Other option is UFO’s are us from the future which would explain the interest.

Imagine if some guy who didn’t ever work at propulsion laboratories or have any degrees, was so intrigued by the concept of a ship smoothly accelerating to light speed and down again, that he thought up a prototype of a mechanical drive system you could bolt to the output shaft of a Bell helicopter for example…. instead of the rotor. And it would take the power of the motor turning and direct it in a direction without needing atmosphere molecules to push against. And the thing didn’t have to many more parts than the rotor blade cyclic and wasn’t that much more complex of a mechanical assembly.

Certainly a very tough technical challenge. I hope they give it a shot. This topic has really inspired (for me, anyway) a desire to understand the incredible distances involved, even to our nearest star buddy. (My apologies for ranting at your writers!) Really looking forward to the JWT and what it may see. in other news I got a great Craigslist deal on a telescope this past weekend…. not a great quality reflector, but enough to enjoy the stars and let my imagination fill in the rest. Cheers.

The speed of light c is NOT a “speed limit” for motion between heavenly bodies. We know this to be true because we observe Doppler redshifts as great as z = 6.3 for the recession rate of distant galaxies, which indicate velocities relative to us that exceed c. The constancy of the line element ds postulated by Einstein’s special theory is not required to ensure that c remains constant in all frames. It is instead the constancy of the phase phi that is required where phi = k dot r minus omega dot t, at any location r and time of observation t for a wave number of k and a wave frequency of omega, The conundrum of space travel will disappear when the scientific community is able to question the infallibility of Einstein’s invariance theories,

I don’t know what that has to do with this project, but such shifts don’t indicate superluminal velocities at all, or even in the case of Newtonian physics for sound. If a receding police car were emitting a 1000 Hz tone, it could be reduced to 1 Hz or less if the car was nearly reaching the speed of sound; but not exceeding it.

Forget the sound analogy. Light travels freely in a vacuum, whereas sound does not and is a disturbance in some medium. This article assumes that the speed of light c is absolute and cannot be exceeded. But that is an error which has led to a lot of silly proposals such as lightsail spacecraft. An intelligent discussion of timely travel to some star such as Alpha Centauri must address whether or not the speed of light can be exceeded. The definition of z is z = omega-emitted divided by omega-observed minus 1 for a light ray emitted by a star, and a value of z = 6.3 indicates a speed greater than c. See, e.g., http://www.astro.ucla.edu/~wright/doppler.htm .

Slowing the probe down is quite possible. The sail would simply have the ability to re-align its sail in opposition to the star as it approaches, causing the incoming photons to push it in the opposite direction, acting as a brake. The nice part about alpha centauri is that there are multiple stars to steer towards and multiple opportunities to slow down based on how the trajectory is altered. The probe would ave to have to computing power to auto-navigate this far from home. The likelihood of instant destruction by space dust is a real concern, which is why multiple probes should be sent. Has anyone made a rudimentary calculation about what the odds are of this happening? This would in turn affect how many probes should be sent,

There is ~ 1 particle, <100 nanometers in size, per running 1,000 kilometers of 1 meter cross-section. At 0.2c therefore, there will be 60 strikes per second (c=300,000 km/s). Most of these will be only a few molecules in size, but even that may have an impact on a membrane <1 micrometer in thickness. A little bigger, and you will get micropunctures big enough to locally interfere with the reflectance of the presumably diachroic mirror-surface. Even assuming the extremely dubious claim that the diachroic integrity over the entire meter or more of sail at the time of manufacture such that the staggering flux of the (even monochromatically tuned) lasers is able to be sustained at such reflectance at every point on the surface, even sub-micron punctures would present a local breakdown in the reflectance/absorption fraction and the laser would then tear away at those poorly reflecting hole-perimeters in seconds, or even milliseconds. The only recourse then is to reduce the flux and extend the propulsion phase. But the thing must still hold up under the dust-flux that much longer. Now we’re talking many strikes by ~100 nanometer grains and the sail would quickly be full of holes, as would a Whipple shield.

Elon Musk’s Hyperloop has a better chance, which is next to nil.

P.S. Once the propulsion phase is completed, of course, the sail no longer matters, and in fact could be collapsed into a compact form directly in front of the probe as a protective barrier.

I forgot to add an answer to the question ‘how many would have to be deployed?’ I’d say ‘All of them.’, and leave it at that.

May I suggest a book, “The Discoverers,” by Daniel Boorstin. This scientific dogma that you preach is ego-based and not accurate historically. In my opinion, there will be new discoveries in the upcoming decades that will cause a complete recalculation of the universe. My guess is that a new dimension will finally be proven that changes the distances that will be measured by actual distances and/or a totally different view of the universe as it actually is. The paradigm will shift once again and the academics will have to completely change their tunes, once again. It’s funny how that has happened over and over throughout human history, but certain scientists still have the audacity to shout never. Your friend, Albert Galileo Copernicus Newton

Light sails are of course an old idea explored in science fiction. That doesn’t mean they are nonsense. As for decelerating, see for example “The Mote In God’s Eye” by Niven and Pournelle.

Comments are closed.

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This is how many people we’d have to send to Proxima Centauri to make sure someone actually arrives

• Emerging Technology from the arXiv archive page

If humans are ever to colonize the galaxy, we will need to make the trip to a nearby star with a habitable planet. Last year, astronomers raised the possibility that our nearest neighbor, Proxima Centauri, has several potentially habitable exoplanets that could fit the bill.

Proxima Centauri is 4.2 light-years from Earth, a distance that would take about 6,300 years to travel using current technology. Such a trip would take many generations. Indeed, most of the humans involved would never see Earth or its exoplanet counterpart. These humans would need to reproduce with each other throughout the journey in a way that guarantees arrival of a healthy crew at Proxima Centauri.

And that raises an interesting question. What is the smallest crew that could maintain a genetically healthy population over that time frame?

Today, we get an answer thanks to the work of Frédéric Marin at the University of Strasbourg and Camille Beluffi at the research company Casc4de, both in France. They have calculated the likelihood of survival for various-sized missions and the breeding rules that will be required to achieve success.

First, some background. Space scientists and engineers have studied various ways of reaching nearby stars. The problem, of course, is the vast distances involved and the comparatively sedate speeds that human spacecraft can manage.

Apollo 11 travelled at around 40,000 kilometers per hour, a speed that would take it to Proxima Centauri in over 100,000 years. But spacecraft have since become faster. The Parker Solar Probe, to be launched this year, will travel at more than 700,000 kilometers per hour, about 0.067 percent the seed of light.

So Marin and Beluffi use this as the speed achievable with state-of-the-art space technology today. “At this speed, an interstellar journey would still take about 6,300 years to reach Proxima Centauri b,” they say.

Selecting a crew for such a multigenerational space journey would be no easy feat. Important parameters include the initial number of men and women in the crew, their age and life expectancy, infertility rates, the maximum capacity of the ship, and so on. It also requires rules about the age at which procreation is permitted, how closely related parents can be, how many children they can have, and so on.

Once these parameters are determined, they can be plugged into an algorithm called Heritage, which simulates a multigenerational mission. First, the algorithm creates a crew with the selected qualities. It then runs through the mission, allowing for natural and accidental deaths each year and checking to see which crew members are within the allowed procreational window.

Next, it randomly associates two crew members of different sexes and evaluates whether they can have a child based on infertility rates, pregnancy chances, and inbreeding limitations. If the pregnancy is deemed viable, the algorithm creates a new crew member and then repeats this loop until the crew either dies out or reaches Proxima Centauri after 6,300 years.

Each mission also includes a catastrophe of some kind—a plague, collision, or other accident—that reduces the crew by a third.

The algorithm then repeats each mission 100 times to determine the likelihood of this size of crew reaching its destination.

A key question is what degree of inbreeding can be allowed. Marin and Beluffi measure this using a scale in which breeding between identical twins registers as 100 percent; brother/sister, father/daughter, or mother/son is 25 percent; uncle/niece or aunt/nephew is 12.5 percent; and first cousins is 6.25 percent.

One option is to limit inbreeding to less than 5 percent, so partners have to be more distantly related than first cousins. Another option is to stipulate that partners cannot be related at all, so that inbreeding is 0. Marin and Beluffi use this second scenario in their simulation.

The algorithm then determines the likelihood of success over 100 missions for different initial crew sizes.

The results make for interesting reading. The Heritage algorithm predicts that an initial crew of 14 breeding pairs has zero chance of reaching Proxima Centauri. Such a small group does not have enough genetic diversity to survive.

Researchers have observed with animals that the genetic diversity of an initial population of 25 pairs can be sustained indefinitely with careful breeding. But when the Heritage algorithm uses this as the starting crew—25 men and 25 women—it predicts a 50 percent chance of dying out before reaching the destination. That’s largely because of random events that can influence such a mission.

The chances of success, according to Heritage, do not reach 100 percent until the initial crew has 98 settlers, or 49 breeding pairs. “We can then conclude that, under the parameters used for those simulations, a minimum crew of 98 settlers is needed for a 6,300-year multi-generational space journey towards Proxima Centauri b,” say Marin and Beluffi.

That’s interesting work that sets the stage for more detailed simulations. For example, fertility rates in deep space may turn out to be quite different from those on Earth. And the chances of a healthy child resulting from a successful pregnancy may also be much lower because of higher mutation rates due to radiation.

The chances of catastrophe because of accidents or plagues may turn out to be much smaller than the chances of catastrophe caused by social factors such as conflict. All this could be programmed into a more advanced version of Heritage.

Indeed, these issues have already been explored by science fiction writers. For example, in the book Seveneves , the author Neal Stephenson imagines a future in which humanity passes through a population bottleneck and all individuals are descended from seven women.

Given Marin and Beluffi’s work, Stephenson’s imagined future looks highly unlikely. But it is surely important to consider the scenario given the multiple threats that our civilization faces. 

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How Long Would it Take to Travel to the Nearest Star?

How far is a light-year?

Why use light-years, alternatives to light-years.

A light-year is a measurement of distance and not time (as the name might imply). A light-year is the distance a beam of light travels in a single Earth year, which equates to approximately 6 trillion miles (9.7 trillion kilometers). 

On the scale of the universe , measuring distances in miles or kilometers is cumbersome given the exceedingly large numbers being discussed. It is much simpler for astronomers to measure the distances of stars from us in the time it takes for light to travel that expanse. For example, the nearest star to our sun , Proxima Centauri , is 4.2 light-years away, meaning the light we see from the star takes a little over four years to reach us. 

The speed of light is constant throughout the universe and is known to high precision. In a vacuum, light travels at 670,616,629 mph (1,079,252,849 km/h). To find the distance of a light-year, you multiply this speed by the number of hours in a year (8,766). The result: One light-year equals 5,878,625,370,000 miles (9.5 trillion km). At first glance, this may seem like an extreme distance, but the enormous scale of the universe dwarfs this length. One estimate puts the diameter of the known universe at 28 billion light-years in diameter .

Measuring in miles or kilometers at an astronomical scale is impractical given the scale of figures being used. Starting in our cosmic neighborhood, the closest star-forming region to us, the Orion Nebula , is a short 7,861,000,000,000,000 miles away, or expressed in light-years, 1,300 light-years away. The center of our galaxy is about 27,000 light-years away. The nearest spiral galaxy to ours, the Andromeda galaxy , is 2.5 million light-years away. Some of the most distant galaxies we can see are billions of light-years from us. The galaxy GN-z11 is thought to be the farthest detectable galaxy from Earth at 13.4 billion light-years away.

Like degrees, the light-year can also be broken down into smaller units of light-hours, light-minutes or light-seconds. For instance, the sun is more than 8 light-minutes from Earth, while the moon is just over a light-second away. Scientists use these terms when talking about communications with deep-space satellites or rovers. Because of the finite speed of light, it can take more than 20 minutes to send a signal to the Curiosity rover on Mars .

Measuring in light-years also allows astronomers to determine how far back in time they are viewing. Because light takes time to travel to our eyes, everything we view in the night sky has already happened. In other words, when you observe something 1 light-year away, you see it as it appeared exactly one year ago. We see the Andromeda galaxy as it appeared 2.5 million years ago. The most distant object we can see, the cosmic microwave background , is also our oldest view of the universe, occurring just after the Big Bang some 13.8 billion years ago.

Astronomers also use parsecs as an alternative to the light-year. Short for parallax-second, a parsec comes from the use of triangulation to determine the distance of stars. To be more specific, it is the distance to a star whose apparent position shifts by 1 arcsecond (1/3,600 of a degree) in the sky after Earth orbits halfway around the sun. One arcsecond is equal to 3.26 light-years.

Whether it's light-years or parsecs, astronomers will continue to use both to measure distances in our expansive and grand universe. 

Additional resources: 

• Watch astronomer Paul Sutter's " We Don't Planet" Episode 9: The Cosmic Distance Ladder . 
• Learn more about how astronomers measure the universe , from the International Astronomical Union.
• Watch " Powers of Ten" (1977) , which gives perspective on the size of the universe.

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Jonathan is the Editor of All About History magazine. He has a degree in History from the University of Leeds. He has previously worked as editor of video game magazines games™ and X-ONE and tech magazines iCreate and Apps. He is currently based in Bournemouth, UK.

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How Far is a Light Year?

How far is a light-year ? It might seem like a weird question because isn’t a ‘year’ a unit of time, and ‘far’ a unit of distance? While that is correct, a ‘light-year’ is actually a measure of distance. A light-year is the distance light can travel in one year.

Light is the fastest thing in our Universe traveling through interstellar space at 186,000 miles/second (300,000 km/sec). In one year, light can travel 5.88 trillion miles (9.46 trillion km).

A light year is a basic unit astronomers use to measure the vast distances in space.

To give you a great example of how far a light year actually is, it will take Voyager 1 (NASA’s longest-lived spacecraft) over 17,000 years to reach 1 light year in distance traveling at a speed of 61,000 kph.

Related Post: 13 Amazing Facts About Space

Why Do We Use Light-Years?

Because space is so vast, the measurements we use here on Earth are not very helpful and would result in enormous numbers.

When talking about locations in our own galaxy we would have numbers with over 18 zeros. Instead, astronomers use light-time measurements to measure vast distances in space. A light-time measurement is how far light can travel in a given increment of time.

• Light-minute: 11,160,000 miles
• Light-hour: 671 million miles
• Light-year: 5.88 trillion miles

Understanding Light-Years

To help wrap our heads around how to use light-years, let’s look at how far things are away from the Earth starting with our closest neighbor, the Moon.

The Moon is 1.3 light-seconds from the Earth.

Earth is about 8 light-minutes (~92 million miles) away from the Sun. This means light from the Sun takes 8 minutes to reach us.

Jupiter is approximately 35 light minutes from the Earth. This means if you shone a light from Earth it would take about a half hour for it to hit Jupiter.

Pluto is not the edge of our solar system, in fact, past Pluto, there is the Kieper Belt , and past this is the Oort Cloud . The Oort cloud is a spherical layer of icy objects surrounding our entire solar system.

If you could travel at the speed of light, it would take you 1.87 years to reach the edge of the Oort cloud. This means that our solar system is about 4 light-years across from edge to edge of the Oort Cloud.

The distance between the Sun and Interstellar Space. NASA/JPL-Caltech .

The nearest known exoplanet orbits the star Proxima Centauri , which is four light years away (~24 trillion miles). If a modern-day jet were to fly to this exoplanet it would not arrive for 5 million years.

One of the most distant exoplanets is 3,000 light-years (17.6 quadrillion miles) away from us in the Milky Way. If you were to travel at 60 miles an hour, you would not reach this exoplanet for 28 billion years.

Our Milky Way galaxy is approximately 100,000 light-years across (~588 quadrillion miles). Moving further into our Universe, our nearest neighbor, the Andromeda galaxy is 2.537 million light-years (14.7 quintillion miles) away from us.

The Andromeda Galaxy is 2.537 million light-years away from us.

Light, a Window into the Past

While we cannot actually travel through time, we can see into the past. How? We see objects because they either emit light or light has bounced off their surface and is traveling back to us.

Even though light is the fastest thing in our Universe, it takes time to reach us. This means that for any object we are seeing it how it was in the past. How far in the past? However long it took the light to reach us.

For day-to-day objects like a book or your dog, it takes a mere fraction of a fraction of a second for the light bouncing off the object to reach your eye. The further away an object is, the further into its past you are looking.

For instance, light from the Sun takes about 8 minutes to reach Earth, this means we are always seeing the Sun how it looked 8 minutes ago if you were on its surface.

The differences between Lunar Distance, an Astronomical Unit, and a Light Year. Illustration by Star Walk .

Traveling back through our solar system, Jupiter is approximately 30 light-minutes from Earth, so we see Jupiter how it looked 30 minutes ago if you were on its surface. Extending out into the Universe to our neighbor the Andromeda galaxy, we see it how it was 2.537 million years ago.

If there is another civilization out in the Universe watching Earth, they would not see us here today, they would see Earth in the past. A civilization that lives 65 million light-years away would see dinosaurs roaming the Earth.

Helpful Resources:

• How big is the Solar System? (Universe Today)
• What is an Astronomical Unit? (EarthSky)
• How close is Proxima Centauri? (NASA Imagine The Universe)

Lightyears 101: Are We Watching the Stars In Real Time?

One lightyear can take you 6 trillion miles away in space..

Rupendra Brahambhatt

Yuri_B/Pixabay

In our solar system, Saturn is the farthest planet from Earth that can be seen with the naked eye. And if it is destroyed by an asteroid while you are watching it (with or without a telescope), the ringed planet would still be visible to you for around 80 minutes, on average, even after it’s in bits and pieces. This happens because the average distance between Saturn and Earth is 0.00015 light-years, which means that the light from Saturn takes approximately 80 minutes to reach your eyes at Earth. 

So if any star that you are observing from Earth is 100 light-years away then what you are watching from your telescope is not its current status but what the star was 100 years ago. This is also why sometimes telescope is called an astronomical time machine . Measuring astronomical distances in miles or kilometers is impractical because of the huge distances and the scale of figures being used. Measuring in light years also allows astronomers to look back in time. Because light takes a standard amount of time to travel to our eyes, everything we can view in space has already happened. So, when you observe something exactly two lightyears away, you see it as it appeared exactly two years ago. 

What is a lightyear?

The speed of light is a constant. In a vacuum, light also travels at speed of 670,616,629 mph (1,079,252,849 km/h). In one Earth year of 364.25 days (8,766 hours), light travels a distance of 5,878,625,370,000 miles (9.5 trillion km). This distance is referred to as one light year.

Since the distance between cosmic bodies mostly came out in the form of millions and billions of kilometers, a more convenient measuring unit was required to easily express such large distances and this led to the lightyear being used as a unit for measuring astronomical distances.

As the value suggests, light year (or lightyear/ly) is a unit of distance. One common misconception about lightyear is that it is a unit of time, which is wrong. Lightyear is generally used to express the distance between Earth and celestial bodies outside our solar system. 

Speed of light and the discovery of lightyear

For scientists to correctly figure out light year, it was important that they have the value of the speed of light. The ancient Greek philosophers disagreed onthe nature of light speed. The philosopher  Empedocles thought that light traveled and so must have a rate of travel. Aristotle, in contrast, argued that light was instantaneous.

In the mid-1600s, Galileo Galilei conducted experiments on the speed of light using people placed on hills around a mile apart, holding lanterns.  But the distance wasn’t far enough to record the speed of light, only to conclude that light traveled faster than sound.

In 1676, Danish astronomer Ole Rømer , accidentally came up with a new estimate for the speed of light, while trying to create a reliable astronomical clock for sailors at sea. He used observations of the eclipses of Jupiter’s moon, Io, to estimate the speed of light at about 124,000 miles per second (200,000 km/s).

However, this is different from the speed of light that we know today (299,792 km/s), but this anomaly was not because Rømer’s method was flawed, but due to the fact that at that time the actual diameter of Earth (12,742 km) was not known. Later, Dutch mathematician Christiaan Huygens calculated the speed of light as 220 thousand miles per second (much closer to the actual) by applying the true value of Earth’s diameter in Rømer’s calculations. 

In 1729, English astronomer James Bradley put forward his theory concerning aberration of light (apparent motion of stars relative to their velocity) before the Royal Society. In his study, he estimated the speed of light at 185,000 miles per second (301,000 km/s) , which is within about 1% of the value that we know today. 

Two separate attempts in the mid-1800s, by French physicists Hippolyte Fizeau and Leon Foucault, each came within about 1,000 miles per second (1,609 km/s) of the speed of light.

In 1879, physicist Albert A. Michelson used mirrors and lenses to measure the speed of light at 186,355 miles per second (299,910 km/s). Forty years later, he used a mile-long depressurized tube of corrugated steel pipe to simulate a near-vacuum and give a better measurement, which was only slightly lower than the accepted value of the speed of light today.  

In 1838, German physicist Friedrich Wilhelm Bessel used the value of the speed of light to measure the distance between Earth and binary star system 61 Cygni. Though he didn’t explicitly mention the word ‘light year’, he explained that light would take 10.3 years to reach from 61 Cygni to Earth. This was the first time, a physicist used light year as the measure of distance, and therefore, Bessel is also credited as the person who discovered lightyear. 

The term ‘lightyear’ was mentioned for the first time in a Germany-based publication called Lichtjare in the year 1851. By the time Einstein came up with his theory of Special Relativity (E=mc 2 ) positing that light always travels with a finite speed, lightyear had already become a popular unit for measuring astronomical distances among scientists.

Light year vs astronomical unit vs lunar distance vs parsec

Apart from lightyear, there are other units as well such as astronomical unit (AU), lunar distance (LD), and parsec (pc) which are used to measure the distance between different objects in space. In astronomy, lunar distance,  or Earth-moon characteristic distance, is the semi-major axis of the geocentric lunar orbit. It is approximately 400,000  km , which is a quarter of a million miles, or 1.28 light seconds. Lunar distance is commonly used to express the distance to near-Earth object encounters. 

An astronomical unit (AU) is equal to the mean distance from the center of the Earth to the center of the sun.

Both lunar distance and astronomical units are used to express the distance between objects within our solar system whereas, lightyear and parsec are employed to measure the distances outside our solar system (such as the distance between galaxies).

A Parsec is the distance at which the radius of  Earth ’s  orbit  subtends an angle of one second of arc (an angle is subtended by an arc when its two rays pass through the endpoints of that arc). Thus, a  star  at a distance of one parsec would have a  parallax  (the angular difference in direction of a celestial body as measured from two points on the Earth’s orbit) of one second.  One lightyear is equal to 63,241 AU but one parsec is equal to 3.26 ly or 206,265 AU.  

Some interesting facts about light years

A lightyear can be further divided into light hours, light minutes, light seconds, and even light nanoseconds, for example, light from the Sun takes eight minutes to reach Earth, which also means that Sun is eight light minutes away from Earth. Here are some interesting facts related to lightyears:

RECOMMENDED ARTICLES

• Voyager 1, a space probe launched by NASA in 1977 transmitted a signal in November 2021 from a distance of 21.31 light hours (14.45 billion miles). This is the farthest distance any artificial object has traveled in space.
• The nearestknown galaxy to the Milky Way (our galaxy) is the Canis Major Dwarf Galaxy, which is 25,000 light years from the Sun. The Sagittarius Dwarf Elliptical Galaxy is the next closest  at 70,000 light years from the Sun.  The most distantly located known-galaxy from Earth is called GN-z11, it was detected by the Hubble telescope in 2016 and at that time it was believed to be 13.4 billion light years away from Earth, or 134 nonillion kilometers (that’s 134 followed by 30 zeros). 
• A radar system that uses radio waves to detect a flying aircraft measures time in nanoseconds to figure out how far a target is because radio waves travel at the speed of light. A nanosecond is equal to one billionth part of a second. L ight travels at 1 foot (30cm) per nanosecond.  
• NASA recently claimed that its Parker Solar probe has “touched the Sun”. It is also believed to be the fastest human-made object in space and is expected to reach speeds of 430,000 mph (690,000 kph) . That’s fast enough to get from Philadelphia to Washington, D.C., in under a second. 

Great American astronomer Edwin Hubble once said, “The search will continue, the urge is older than history, it is not satisfied and will not be suppressed”. Space exploration can also be considered a search for what lies beyond Earth and stars. As a unit of distance, the lightyear is also a reminder to us of just how vast the universe is, and how much humanity and science still have to learn.

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By Darin Anthony - Last Updated: April 17, 2024

How Long Would It Take to Travel One Light Year?

Article Contents

We hear the term “light-years” almost anytime a new star or exo-planet is discovered. But how long would it take to travel one light year?

The fastest human-made vehicle, NASA’s Parker Solar Probe, would take 1,698 years to travel one light-year , the sum of roughly 5.88 trillion miles (9.46 trillion kilometers), the distance light travels in one year.

In September 2023, NASA’s Parker Solar Probe set a new record, clocking a blistering speed of 394,736 miles per hour (635,266 kilometers per hour)—the fastest ever recorded.

But 1,698 years is an incredibly long time. The Parker Solar Probe would have just completed a distance of one light year if it had left during the 4th century (326 A.D.) and maintained its top speed the entire journey.

Let’s look more closely at the speed of light and what it means to travel one light-year.

Understanding Light Years

Speed of light.

Over one hundred years ago, Albert Einstein’s theory of relativity deciphered the math of a cosmic limit. It says nothing can go faster than  the speed of light , which is approximately 186,282 miles per second (299,792 km/s) within the vacuum of space.

To help understand how fast light speed is, we’ll compare it to the longest intercontinental flight in the world today.

A flight from New York to Singapore covers 9,526 miles (15.332km) and, on average, takes 18hrs 40 minutes. If a commercial airliner could travel the speed of light, symbolically, it could make that trip almost 20 times in one second!

Measuring Distances

Understanding the vastness of space begins with grasping the concept of a light-year . It’s a unit of measurement scientists use to note the length of astronomical distances.

Astronomers use two common measurements to help make an incredibly long distance, a huge number, more manageable.

Astronomical Unit (AU) : It’s the distance the Sun’s light takes to reach the Earth. This distance is approximately 93 million miles (150 million kilometers) and takes eight light minutes.

Light-Year (LY): It represents the unit of distance that light travels in one Earth year , which is approximately 5.88 trillion miles (9.46 trillion kilometers).

So, the time it takes Light to travel one light year? One Earth year or roughly 365 days .

When speaking of distances in the universe, an astronomer refers to distances in an (AU) or (LY) depending on how great of a distance.

For example, when referring to the distance of the Andromeda Galaxy from Earth, it is stated as 2.5m (LY) light years( i ). However, the shorter distance to Neptune from the Sun is noted as approximately 30.7 (AU)( i ).

Since a light-year is a larger unit of distance than (AU) it is more likely to be used when expressing bigger numbers.

Travel Time

If we could travel the distance of one light-year from Earth, we would end up in the mid-region of the Oort cloud .

It is the outermost area of our solar system before reaching the realm of deep outer space. The time it would take to journey this one light-year would greatly depend on our mode of transportation.

I’ve put together several calculations using a light-year (ly) calculator. Using the average miles per hour (mph) for current technology we use today. It makes the complexity of traversing such an immense distance very obvious.

See the infographic I have provided below, which has a link to the calculator within the caption.

Let’s look at some of the examples the infographic highlights in relation to how long it takes to travel a light-year.

If you decide to put on some walking shoes and head off towards the mid-region of the Oort cloud , a light year away, be sure to pack lunch. At a normal pace of 3/mph, it would take nearly 224 million years to get there without stopping to eat, sleep, or bathroom breaks.

Walking (3/mph) >>> One Light Year >>> 224M Years

You could pull the car cover off the Corvette stored in the garage for a quicker ride. Even then, traveling at an average speed of 100 mph would take six million and seven hundred thousand years (6.7m years) to travel a light year . That’s without stopping or slowing down.

Drive (100/mph) >>> One Light Year >>> 6.7M Years

How about a ticket on the “Big ol’ Jet Airliner”? It would still take you over one million years (1.118m yrs) to span the distance of one light year on a commercial Jet .

Commercial Jet (600/mph) >>> One Light Year >>> 1.18M Years

The point is that the distances between objects in our solar system, galaxy, and universe are so vast it’s very challenging for our minds to grasp and comprehend it.

As of today, we do not have technology that can travel the distance of a light-year within the span of a human life, but there are future concepts. Let’s take a look.

Future Concepts to Travel Light-Years

Considering our Milky Way galaxy stretches across 100,000 light-years. Even at the speed of light, it takes 100,000 Earth years to journey from edge to edge. To bridge that distance, we’ll need to inspire some new ideas through quantum physics.

But some interesting concepts are in the works right now to dramatically shorten the length of time it takes to travel a light year.

Breakthrough Starshot

In 2016, Physicist Yuri Milner announced an engineering endeavor named “ Breakthrough Starshot ,” with backing support from such notable figures as Stephen Hawking (now deceased), and Mark Zuckerberg.

Their aim is to develop a fleet of light sail centimeter-sized probes called StarChips . These probes are designed to travel to the Alpha Centauri star system , located 4.37 light-years away, potentially within 20 to 30 years at speeds of 15-20% the speed of light.

Currently, using the Parker Solar Probe’s top speed, to travel 4 light-years would take over 7000 years, so that would be an amazing feat.

The project proposes a flyby mission to our next closest star beyond our Sun, Proxima Centauri. It is believed to be home to an Earth-sized exoplanet in the habitable zone.

The concept will leverage advanced laser technology to propel the spacecraft. Current estimates for launch are 2036.

Helical Engine

A space and aeronautics engineer has developed a concept that, in theory, would reach 99% of the speed of light without conflicting with Einstein’s theory of relativity .

Dr Burn, now a former engineer from NASA’s Space Flight Center in Alabama , believes that a system where instead of expelling propellant, it is retained, could generate an almost limitless specific impulse and open the door to interstellar space exploration.

This method involves accelerating ions near the light speed limit within a closed circuit, adjusting their speed to modify momentum. Thrust is generated by oscillating the ions back and forth in the direction of travel.

It’s Designed for long-term satellite operations without the need for refueling or powering voyages across vast distances; this engine operates without any mechanical components, relying solely on ions circulating in a vacuum loop contained by electric and magnetic fields.

If this concept is proven and successful it would mean we could travel a light-year in a little more than one year!

It’s impossible to talk about traveling at the speed of light without discussing the theory of warp drive , which was popularized by the 1960s Star Trek series.

NASA has explored this concept and will continue to do so as science and modern physics expand with future breakthroughs.

The idea behind warp drive is to manipulate the fabric of spacetime to create a bubble or a wave, often referred to as a “ warp bubble ,” that would contract space in front of the ship and expand it from behind , allowing the vessel to move from one point to another faster than light would in normal space.

It would theoretically enable interstellar travel within human lifetimes without violating the fundamental principles of Einstein’s theory of general relativity, which states that nothing can travel faster than the speed of light in a vacuum.

If this concept is ever proven, it will be a game changer for space travel in our cosmic neighborhood and beyond.

For now, the Parker Solar Probe’s top speed makes it the fastest vehicle to span the distance of a light year . The enormity of the universe will make reaching distant stars and exoplanets impossible until we can develop technologies like the Warp Drive, Starshot, or Helical engine.

It’s a humbling distance across our Milky Way. But scientists continue to unlock the mysteries of the cosmos, and one day, we may crack the code to bridge the vast galactic space within the universe.

Astronomy has peaked my curiosity and imagination from an early age. I am always thrilled to read about the latest galactic discovery or planning my next celestial observation. More about me [..]

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Is Time Travel Possible?

We all travel in time! We travel one year in time between birthdays, for example. And we are all traveling in time at approximately the same speed: 1 second per second.

We typically experience time at one second per second. Credit: NASA/JPL-Caltech

NASA's space telescopes also give us a way to look back in time. Telescopes help us see stars and galaxies that are very far away . It takes a long time for the light from faraway galaxies to reach us. So, when we look into the sky with a telescope, we are seeing what those stars and galaxies looked like a very long time ago.

However, when we think of the phrase "time travel," we are usually thinking of traveling faster than 1 second per second. That kind of time travel sounds like something you'd only see in movies or science fiction books. Could it be real? Science says yes!

This image from the Hubble Space Telescope shows galaxies that are very far away as they existed a very long time ago. Credit: NASA, ESA and R. Thompson (Univ. Arizona)

How do we know that time travel is possible?

More than 100 years ago, a famous scientist named Albert Einstein came up with an idea about how time works. He called it relativity. This theory says that time and space are linked together. Einstein also said our universe has a speed limit: nothing can travel faster than the speed of light (186,000 miles per second).

Einstein's theory of relativity says that space and time are linked together. Credit: NASA/JPL-Caltech

What does this mean for time travel? Well, according to this theory, the faster you travel, the slower you experience time. Scientists have done some experiments to show that this is true.

For example, there was an experiment that used two clocks set to the exact same time. One clock stayed on Earth, while the other flew in an airplane (going in the same direction Earth rotates).

After the airplane flew around the world, scientists compared the two clocks. The clock on the fast-moving airplane was slightly behind the clock on the ground. So, the clock on the airplane was traveling slightly slower in time than 1 second per second.

Credit: NASA/JPL-Caltech

Can we use time travel in everyday life?

We can't use a time machine to travel hundreds of years into the past or future. That kind of time travel only happens in books and movies. But the math of time travel does affect the things we use every day.

For example, we use GPS satellites to help us figure out how to get to new places. (Check out our video about how GPS satellites work .) NASA scientists also use a high-accuracy version of GPS to keep track of where satellites are in space. But did you know that GPS relies on time-travel calculations to help you get around town?

GPS satellites orbit around Earth very quickly at about 8,700 miles (14,000 kilometers) per hour. This slows down GPS satellite clocks by a small fraction of a second (similar to the airplane example above).

GPS satellites orbit around Earth at about 8,700 miles (14,000 kilometers) per hour. Credit: GPS.gov

However, the satellites are also orbiting Earth about 12,550 miles (20,200 km) above the surface. This actually speeds up GPS satellite clocks by a slighter larger fraction of a second.

Here's how: Einstein's theory also says that gravity curves space and time, causing the passage of time to slow down. High up where the satellites orbit, Earth's gravity is much weaker. This causes the clocks on GPS satellites to run faster than clocks on the ground.

The combined result is that the clocks on GPS satellites experience time at a rate slightly faster than 1 second per second. Luckily, scientists can use math to correct these differences in time.

If scientists didn't correct the GPS clocks, there would be big problems. GPS satellites wouldn't be able to correctly calculate their position or yours. The errors would add up to a few miles each day, which is a big deal. GPS maps might think your home is nowhere near where it actually is!

In Summary:

Yes, time travel is indeed a real thing. But it's not quite what you've probably seen in the movies. Under certain conditions, it is possible to experience time passing at a different rate than 1 second per second. And there are important reasons why we need to understand this real-world form of time travel.

If you liked this, you may like:

CalcuNation

Light Year Distance Calculator

Calculate the distance light can travel in a given amount of time with this online calculator.

How do you calculate light year distance?

A light year is a measurement of distance. This distance is measured by how far light can travel in a year.

Light travels at approximately 186,000 miles per second.

In one year (365.25 days) that is equivalent to 5,869,713,600,000 miles.

Example: How far does light travel in 3 months.

3 months is 1/4 year. So enter .25 in the calculator to determine the distance that light travels in 3 months.

Answer: 1,467,428,400,000 miles

Related Calculators

Convert 4 Light Years to Miles

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How long is a year on other planets?

The planets within our solar system are in constant motion in their orbits and as they spin on their axes. All planets in our solar system revolve around the Sun. But the time they take to complete one revolution around our central star differs. While some planets take days, others take much longer. Here’s a look at how long a year is on each of the planets, in Earth days:

• Mercury – 88 Earth days
• Venus – 225 Earth days
• Earth – 365 days
• Mars – 687 Earth days
• Jupiter – 4,331 Earth days or 12 Earth years
• Saturn- 10,747 Earth days or 29.4 Earth years
• Uranus – 30,589 Earth days or 84 Earth years
• Neptune – 59,800 Earth days or 165 Earth years

Rotation and revolution

Years on other planets are measured using Earth’s tropical year, which lasts about 365 solar days; one solar day is the time it takes our planet to spin, or rotate, once fully on its axis, as measured by the Sun’s position over a given point. A year is measured by how long it takes the planet to orbit the Sun, and one complete orbit is called a revolution.

All planets (and other bodies) in the solar system also do this but, at different speeds. The gas giants Jupiter and Saturn, as well as the ice giants Uranus and Neptune, rotate faster than terrestrial planets like Earth, Mars, Venus, and Mercury. Each planet’s rotation rate is at least partly based on how it formed from the protoplanetary disk surrounding our young Sun. But why the rotation rates of the giant planets are so much faster is still not fully understood.

Related: What time is it on the Moon? | How much you’d weigh on other planets

Laws of motion

Kepler’s third law of motion explains that the time it takes a planet to complete a revolution is related to its distance from our star. Planets farther from the Sun must travel longer paths as they orbit and move slower because the Sun’s gravitational influence diminishes with distance. Conversely, planets closer to the Sun move faster and feel greater gravitational influence from our star.

For example, Mercury, the planet closest to the Sun, takes 88 days to complete a full revolution. The farthest planet from the Sun, Neptune, takes 165 years to finish one orbit around the Sun.

Planets also don’t move at constant speeds throughout their entire orbit. This is because the planets’ orbits are not perfectly circular, but instead slightly out of round, or elliptical (egg-shaped). Kepler’s second law of motion states that when a planet is closer to the Sun in its orbit, it moves faster than when it is farther from the Sun.

Mercury spins on its axis very slowly and completes one rotation every 59 Earth days. However, its orbit around the Sun is speedy compared to other planets. Mercury circles the Sun every 88 Earth days. But the Sun appears to move strangely through Mercury’s sky because the planet’s speed changes, depending on where it happens to be in its elliptical orbit around the Sun. So, one solar day, or complete day-night cycle, takes about 176 Earth days on Mercury.

The hottest planet in the solar system takes about 225 Earth days to complete one rotation around the Sun. Venus spins very slowly and appears to rotate retrograde, or in a clockwise direction – opposite from most planets, which rotate counterclockwise, or prograde, in the same direction as they move through their orbits. It takes Venus 243 Earth days to rotate on its axis once.

RELATED: Why the planets orbit the Sun counterclockwise

It takes Earth exactly 365.25 days to make one complete orbit around the Sun. Earth rotates on its axis once every 23.9 hours.

One year on Mars equals 687 Earth days or 1.88 Earth years. On Mars, solar days are called sols, and one year is also 669.6 sols. Mars’ rotation is similar to Earth’s, and it completes one rotation every 24.6 hours.

Related: What time is it on Mars?

Days are super short on Jupiter. It takes just under 10 hours for the planet to complete one rotation. However, because of its distance, it takes Jupiter 12 Earth years to complete one jovian year. It takes approximately 43 minutes for light from the Sun to reach Jupiter – and just 8 minutes for sunlight to reach Earth by comparison.

Right behind Jupiter with the second-shortest day is Saturn, which completes one rotation every 10.7 Earth hours. Saturn finishes one journey around the Sun every 10,756 Earth days or 29.4 Earth years. Because of its axial tilt of 26.7°, the angle at which we observe Saturn’s rings changes over time. Sometimes we see their northern side, sometimes they appear edge-on, and sometimes we observe the southern side. The next ring plane crossing, when they appear edge-on, is in 2025.

One year on the planet Uranus can last a lifetime! It takes about  84 Earth years for Uranus to complete its orbit around the Sun. However, it only takes 17.2 hours for one day to pass on the planet. Like Venus, Uranus appears to rotate retrograde, or counterclockwise. It also appears to rotate on its side at an angle of 97.8°!

Neptune 

One day on Neptune takes about 16 Earth hours. Its journey around the Sun takes a bit over 165 Earth years, or 59,800 Earth days. Neptune’s axis is tilted at an angle of 28.3°, so it does experience seasons. However, because its year so long, each of the four seasons lasts over 40 years.

Honorable mention: Pluto

Pluto was considered the solar system’s ninth planet for 76 years, from 1930 to 2006. In 2006, Pluto was reclassified as a dwarf planet  by the International Astronomical Union. In total, there are now five recognized dwarf planets. One year on Pluto is 248 Earth years, and its day lasts 153.3 Earth hours (just over 6 Earth days).

How old is each planet in our solar system?

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An expert explains the psychedelic rainbow colors of the aurora

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The northern lights: A history of aurora sightings

How to see the northern lights and what they looked like this weekend.

• International

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The latest on the massive solar storm

By Angela Fritz, Elise Hammond and Chris Lau, CNN

Incredible lighthouse picture from Maine

From CNN's Chris Lau

Among a flurry of surreal images capturing the dazzling auroras is one taken by Benjamin Williamson of a lighthouse in Portland, Maine.

"It's one of the most incredible things I've ever seen, the awe and wonder," Williamson told CNN.

He said he used a long-exposure technique to snap the shot, but did not edit it.

Watch the full interview with Williamson here .

Things could be about to ramp up

If you still haven't seen the aurora, hold on for another 30 minutes to an hour, according to CNN meteorologist Chad Myers.

The next wave of coronal mass ejections, or CMEs, which cause the aurora, is about to arrive, he said.

"Just wait a minute because things are going to start to ramp up here," he said, adding that the increase could arrive "anytime now." "When it comes, get outside, get ready, put your coat on."

For those who are too busy to witness the phenomenon tonight, Myers said the aurora is expected to last three nights.

Why does the aurora last for a weekend?

By CNN's Chris Lau

Generally, it takes just eight minutes for light to travel 93 million miles to the Earth from the sun, but astrophysicist Janna Levin said the energized particles causing the current wave of aurora travel a lot slower, causing the phenomenon to last for the weekend.

"Some of these mass ejections are trillions of kilograms," she said. "They're slower. So they're taking longer, but still hours, maybe tens of hours."

Here's how the solar storm looks in the South and on the East Coast

The aurora was visible across the East Coast and in the South Friday.

Here's how it looked in Chester, South Carolina.

Down in Florida, waves of color swam through the sky.

Up north in New Jersey, a purple-ish haze could be seen in the sky.

Will solar storms get more intense and risky in the future?

The answer is probably not in the short term, according to astrophysicist Hakeem Oluseyi.

He said scientists study what is constantly happening on the surface of the sun and have found a pattern.

“Geological data shows us that in the past the sun was way more active than it is today. It has cycles where it goes very quiet ... and you have events that show that the solar activity was much, much greater,” he told CNN. “So there's no evidence that we're going to see those big maxima this cycle." 

But the astrophysicist also spoke of a caveat - the limitations of modern science.

“Even though it's predictable in the short term, we still don't quite understand what creates the magnetic fields in the sun,” he said, adding: “That's why NASA has so many satellites looking at the sun.”

In Pictures: Auroras light the sky during rare solar storm

From CNN Digital's Photo Team

A series of solar flares and coronal mass ejections from the sun are creating dazzling auroras across the globe .

The rare solar storm may also disrupt communications. The last time a solar storm of this magnitude reached Earth was in October 2003, according to the National Oceanic and Atmospheric Administration's Space Weather Prediction Center.

See more photos of the aurora from tonight.

Behind dazzling aurora could lie “real danger,” Bill Nye the Science Guy says

The massive solar storm could present “a real danger,” especially with the modern world relying so much on electricity, according to Bill Nye the Science Guy , a science educator and engineer.

Scientists are warning an increase in solar flares and coronal mass ejections from the sun have the potential to disrupt communication on Earth into the weekend. Solar flares can affect communications and GPS almost immediately because they disrupt Earth’s ionosphere, or part of the upper atmosphere. Energetic particles released by the sun can also disrupt electronics on spacecraft and affect astronauts without proper protection within 20 minutes to several hours.

In comparison to tonight's event, Nye drew comparisons with another incident in 1859, known as the Carrington Event, when telegraph communications were severely affected.

“The other thing, everybody, that is a real danger to our technological society, different from 1859, is how much we depend on electricity and our electronics and so on,” Nye said. "None of us really in the developed world could go very long without electricity."

He noted that there are systems in place to minimize the impact, but “stuff might go wrong,” stressing that not all transformers are equipped to withstand such a solar event.

“It depends on the strength of the event and it depends on how much of our infrastructures are prepared for this the sort of thing,” he said.

Bill Nye breaks down significance of the solar storm | CNN

This post has been updated with more details on solar flares' impact on electronics.

Here's where clouds will block the view of the northern lights in the US

From CNN's Angela Fritz

After an incredibly stormy week, most of the Lower 48 has clear skies to see the northern lights. But there are some areas where clouds and rainy weather are spoiling the view.

A deck of clouds is blocking the sky in the Northeast, from parts of Virginia into Maine, as an area of low pressure spins off the East Coast.

In the Midwest, the aurora will be hard to see through thick clouds in parts of Wisconsin, Michigan — including the Upper Peninsula — and Illinois.

A stripe of clouds is tracking across Texas, including Dallas-Forth Worth, and into Louisiana.

And in the Southwest, patchy clouds across the the Four Corners region could make the northern lights difficult to spot.

Aurora seen at least as far south as Georgia

Barely visible to the naked eye, the aurora can be seen in Atlanta in the 10 p.m. ET hour. 

It is easier to see through photographs using a long exposure. The photos below, taken by CNN's Eric Zerkel and Emily Smith, used 3- and 10-second exposures.

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Jupiter Facts

Jupiter is a world of extremes. It's the largest planet in our solar system – if it were a hollow shell, 1,000 Earths could fit inside. It's also the oldest planet, forming from the dust and gases left over from the Sun's formation 4.5 billion years ago. But it has the shortest day in the solar system, taking only 10.5 hours to spin around once on its axis.

Introduction

Jupiter's signature stripes and swirls are actually cold, windy clouds of ammonia and water, floating in an atmosphere of hydrogen and helium. The dark orange stripes are called belts, while the lighter bands are called zones, and they flow east and west in opposite directions. Jupiter’s iconic Great Red Spot is a giant storm bigger than Earth that has raged for hundreds of years.

The king of planets was named for Jupiter, king of the gods in Roman mythology. Most of its moons are also named for mythological characters, figures associated with Jupiter or his Greek counterpart, Zeus.

Jupiter, being the biggest planet, gets its name from the king of the ancient Roman gods.

Potential for Life

Jupiter’s environment is probably not conducive to life as we know it. The temperatures, pressures, and materials that characterize this planet are most likely too extreme and volatile for organisms to adapt to.

While planet Jupiter is an unlikely place for living things to take hold, the same is not true of some of its many moons. Europa is one of the likeliest places to find life elsewhere in our solar system. There is evidence of a vast ocean just beneath its icy crust, where life could possibly be supported.

Size and Distance

With a radius of 43,440.7 miles (69,911 kilometers), Jupiter is 11 times wider than Earth. If Earth were the size of a grape, Jupiter would be about as big as a basketball.

From an average distance of 484 million miles (778 million kilometers), Jupiter is 5.2 astronomical units away from the Sun. One astronomical unit (abbreviated as AU), is the distance from the Sun to Earth. From this distance, it takes sunlight 43 minutes to travel from the Sun to Jupiter.

Orbit and Rotation

Jupiter has the shortest day in the solar system. One day on Jupiter takes only about 10 hours (the time it takes for Jupiter to rotate or spin around once), and Jupiter makes a complete orbit around the Sun (a year in Jovian time) in about 12 Earth years (4,333 Earth days).

Its equator is tilted with respect to its orbital path around the Sun by just 3 degrees. This means Jupiter spins nearly upright and does not have seasons as extreme as other planets do.

With four large moons and many smaller moons, Jupiter forms a kind of miniature solar system.

Jupiter has 95 moons that are officially recognized by the International Astronomical Union. The four largest moons – Io, Europa, Ganymede, and Callisto – were first observed by the astronomer Galileo Galilei in 1610 using an early version of the telescope. These four moons are known today as the Galilean satellites, and they're some of the most fascinating destinations in our solar system.

Io is the most volcanically active body in the solar system. Ganymede is the largest moon in the solar system (even bigger than the planet Mercury). Callisto’s very few small craters indicate a small degree of current surface activity. A liquid-water ocean with the ingredients for life may lie beneath the frozen crust of Europa, the target of NASA's Europa Clipper mission slated to launch in 2024.

› More on Jupiter's Moons

Discovered in 1979 by NASA's Voyager 1 spacecraft, Jupiter's rings were a surprise. The rings are composed of small, dark particles, and they are difficult to see except when backlit by the Sun. Data from the Galileo spacecraft indicate that Jupiter's ring system may be formed by dust kicked up as interplanetary meteoroids smash into the giant planet's small innermost moons.

Jupiter took shape along with rest of the solar system about 4.5 billion years ago. Gravity pulled swirling gas and dust together to form this gas giant. Jupiter took most of the mass left over after the formation of the Sun, ending up with more than twice the combined material of the other bodies in the solar system. In fact, Jupiter has the same ingredients as a star, but it did not grow massive enough to ignite.

About 4 billion years ago, Jupiter settled into its current position in the outer solar system, where it is the fifth planet from the Sun.

The composition of Jupiter is similar to that of the Sun – mostly hydrogen and helium. Deep in the atmosphere, pressure and temperature increase, compressing the hydrogen gas into a liquid. This gives Jupiter the largest ocean in the solar system – an ocean made of hydrogen instead of water. Scientists think that, at depths perhaps halfway to the planet's center, the pressure becomes so great that electrons are squeezed off the hydrogen atoms, making the liquid electrically conducting like metal. Jupiter's fast rotation is thought to drive electrical currents in this region, with the spinning of the liquid metallic hydrogen acting like a dynamo, generating the planet's powerful magnetic field.

Deeper down, Jupiter's central core had long been a mystery. Scientists theorized Jupiter was a mostly homogeneous mix of hydrogen and helium gases, surrounding a small, solid core of heavier elements – ice, rock, and metal formed from debris and small objects swirling around that area of the embryonic solar system 4 billion years ago.

NASA’s Juno spacecraft, measuring Jupiter’s gravity and magnetic field, found data suggesting the core is much larger than expected, and not solid. Instead, it’s partially dissolved, with no clear separation from the metallic hydrogen around it, leading researchers to describe the core as dilute, or “fuzzy.”

As a gas giant, Jupiter doesn’t have a true surface. The planet is mostly swirling gases and liquids. While a spacecraft would have nowhere to land on Jupiter, it wouldn’t be able to fly through unscathed either. The extreme pressures and temperatures deep inside the planet crush, melt, and vaporize spacecraft trying to fly into the planet.

Jupiter's appearance is a tapestry of colorful stripes and spots – the cloud bands that encircle the planet, and the cyclonic storms dotting it from pole to pole. The gas planet likely has three distinct cloud layers in its "skies" that, taken together, span about 44 miles (71 kilometers). The top cloud is probably made of ammonia ice, while the middle layer is likely made of ammonium hydrosulfide crystals. The innermost layer may be made of water ice and vapor.

The vivid colors you see in thick bands across Jupiter may be plumes of sulfur and phosphorus-containing gases rising from the planet's warmer interior. Jupiter's fast rotation – spinning once every 10 hours – creates strong jet streams, separating its clouds into dark belts and bright zones across long stretches.

With no solid surface to slow them down, Jupiter's spots can persist for many years. Stormy Jupiter is swept by over a dozen prevailing winds, some reaching up to 335 miles per hour (539 kilometers per hour) at the equator. The Great Red Spot, a swirling oval of clouds twice as wide as Earth, has been observed on the giant planet for more than 300 years. More recently, three smaller ovals merged to form the Little Red Spot, about half the size of its larger cousin.

Findings from NASA’s Juno probe released in October 2021 provide a fuller picture of what’s going on below those clouds. Data from Juno shows that Jupiter’s cyclones are warmer on top, with lower atmospheric densities, while they are colder at the bottom, with higher densities. Anticyclones, which rotate in the opposite direction, are colder at the top but warmer at the bottom.

The findings also indicate these storms are far taller than expected, with some extending 60 miles (100 kilometers) below the cloud tops and others, including the Great Red Spot, extending over 200 miles (350 kilometers). This surprising discovery demonstrates that the vortices cover regions beyond those where water condenses and clouds form, below the depth where sunlight warms the atmosphere.

The height and size of the Great Red Spot mean the concentration of atmospheric mass within the storm potentially could be detectable by instruments studying Jupiter’s gravity field. Two close Juno flybys over Jupiter’s most famous spot provided the opportunity to search for the storm’s gravity signature and complement the other results on its depth.

With their gravity data, the Juno team was able to constrain the extent of the Great Red Spot to a depth of about 300 miles (500 kilometers) below the cloud tops.

Belts and Zones In addition to cyclones and anticyclones, Jupiter is known for its distinctive belts and zones – white and reddish bands of clouds that wrap around the planet. Strong east-west winds moving in opposite directions separate the bands. Juno previously discovered that these winds, or jet streams, reach depths of about 2,000 miles (roughly 3,200 kilometers). Researchers are still trying to solve the mystery of how the jet streams form. Data collected by Juno during multiple passes reveal one possible clue: that the atmosphere’s ammonia gas travels up and down in remarkable alignment with the observed jet streams.

Juno’s data also shows that the belts and zones undergo a transition around 40 miles (65 kilometers) beneath Jupiter’s water clouds. At shallow depths, Jupiter’s belts are brighter in microwave light than the neighboring zones. But at deeper levels, below the water clouds, the opposite is true – which reveals a similarity to our oceans.

Polar Cyclones Juno previously discovered polygonal arrangements of giant cyclonic storms at both of Jupiter’s poles – eight arranged in an octagonal pattern in the north and five arranged in a pentagonal pattern in the south. Over time, mission scientists determined these atmospheric phenomena are extremely resilient, remaining in the same location.

Juno data also indicates that, like hurricanes on Earth, these cyclones want to move poleward, but cyclones located at the center of each pole push them back. This balance explains where the cyclones reside and the different numbers at each pole.

Magnetosphere

The Jovian magnetosphere is the region of space influenced by Jupiter's powerful magnetic field. It balloons 600,000 to 2 million miles (1 to 3 million kilometers) toward the Sun (seven to 21 times the diameter of Jupiter itself) and tapers into a tadpole-shaped tail extending more than 600 million miles (1 billion kilometers) behind Jupiter, as far as Saturn's orbit. Jupiter's enormous magnetic field is 16 to 54 times as powerful as that of the Earth. It rotates with the planet and sweeps up particles that have an electric charge. Near the planet, the magnetic field traps swarms of charged particles and accelerates them to very high energies, creating intense radiation that bombards the innermost moons and can damage spacecraft.

Jupiter's magnetic field also causes some of the solar system's most spectacular aurorae at the planet's poles.

Discover More Topics From NASA

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• The Inventory

A Planet Just 41 Light-Years From Earth Has an Atmosphere and Is Covered in a Magma Ocean

The webb space telescope has uncovered a nearby rocky planet with a volatile atmosphere..

Scientists have spotted a rocky exoplanet with a possible atmosphere, which they believe may be burbling out from a magma ocean on the distant world.

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The planet is called 55 Cancri e. It’s located about 41 light-years from Earth and, per the team’s observations, has a layer of gases above its surface that may constitute an atmosphere. 55 Cancri e is a super-Earth, a rocky body roughly 8.8 times the size of our world with an equilibrium temperature of about 2,000 Kelvin, or 3,140 degrees Fahrenheit. The team’s findings were published today in Nature.

“55 Cancri e is one of the most enigmatic exoplanets,” said Brice-Olivier Demory, an astrophysicist at the University of Bern and co-author of the study, in a university release. “Despite enormous amounts of observing time obtained with a dozen of ground and space facilities in the past decade, its very nature has remained elusive, until today, when parts of the puzzle could finally be put together thanks to the James Webb Space Telescope (JWST).”

Webb has been conducting scientific operations from a point about one million miles from Earth for nearly two years , yielding plenty of insights into galaxy formation, ancient light sources, distant exoplanets, and even the other worlds in our own solar system. The team studied the exoplanet using Webb’s Near-Infrared Camera (NIRCam) and Mid-InfraRed Instrument (MIRI), its two main imagers. “The measurements rule out the scenario where the planet is a lava world shrouded by a tenuous atmosphere made of vaporized rock,” the researchers wrote in their study, “and indicate a bona fide volatile atmosphere likely rich in [carbon dioxide] or [carbon monoxide].”

The planet is tidally locked, meaning one of its sides faces its host star at all times (like how the Moon’s near side always faces Earth). But measurements of 55 Cancri’s dayside temperature turned out cooler than the team expected—evidence that an atmosphere is distributing heat around the planet.

“There have been many observations of atmospheres on exoplanets, but all of them have massive, hydrogen-dominated atmospheres,” said Renyu Hu, a planetary scientist at NASA’s Jet Propulsion Laboratory and the study’s lead author, in an email to Gizmodo. “Here we finally obtained an observation of an atmosphere surrounding a rocky exoplanet.”

Though 55 Cancri e is not hospitable for life as we know it, it is a useful case study for showing how the Webb telescope can characterize distant worlds without directly imaging them. Rocky exoplanets, as opposed to gigantic gas giants, are very difficult to image directly ; they aren’t bright like stars and are much less massive. Instead, scientists discern aspects of an exoplanet’s makeup using the stars they orbit. The recent research team identified the possible atmosphere on 55 Cancri e by carefully measuring the amount of light that came from the planet as it orbited its star. The next-generation Habitable Worlds Observatory , should it get off the ground, will make it much easier to discern aspects of distant exoplanets, potentially boosting scientists’ ability to find life beyond Earth.

Astronomers have documented more than 5,000 exoplanets to date. These worlds need to be looked at closely for researchers to separate the wheat from the chaff in terms of astrobiology; even looking at the hostile worlds can shed light on how planets evolve and what sort of planetary diversity exists in the cosmos.

In March 2023, a different team of researchers found that the rocky planet TRAPPIST-1b does not have an atmosphere , perhaps because its close proximity to its host star zaps any that the planet may develop. The TRAPPIST-1 system is compelling for astrobiologists because several of its worlds sit in the so-called “habitable zone” that make worlds neither too hot nor too cold for life as we know it to persist.

Atmospheres are crucial for supporting life, so as interest in the TRAPPIST-1 system wanes, 55 Cancri e is emerging as a fascinating candidate for astrobiological studies.

More : The Webb Space Telescope’s Best Images, One Year On

I'm a flight attendant - these are the packing hacks I've learnt from 16 years of working in plane cabins (including why you should avoid cases with hard shells and four wheels)

• Flight attendant Emilie shares her packing tips 
• She has space-saving hacks and tips for packing extra quickly
• READ MORE:  Cunard's latest £500m liner Queen Anne arrives in Southampton  

Summer holidays are on the horizon, which means packing season is close.

And for many, it's always a struggle to get through it without making fundamental errors.

Even frequent fliers are prone to pack pointless items into a case that was never going to fit into an overhead bin.

To help lessen the stress, retailer House of Fraser partnered with flight attendant Emilie and asked her to share her packing tips. She's been working in plane cabins for 16 years – so no amateur when it comes to the art of suitcase management.

Scroll down for her top tips, which include hacks for saving space and ensuring you never leave anything essential behind - and the perils of a hard-shell case.

Try this trick if you're a frequent flyer

Emilie suggests having essentials ready to go, explaining: 'If you're a frequent flyer or tend to have regular staycations, set aside essential travel items in your backpack or weekend bag. For example, power banks, plug adaptors, travel toiletries, medication and sun cream. Having these essentials handy and ready to go can help you pack quickly for your next trip.'

Deploy this tactic and there's little chance of leaving anything behind.

Never pack these items next to each other

Cabin pressure can have adverse effects on your toiletries. Because of this, Emilie advises: 'The change in air pressure can sometimes cause liquids to leak, even if they are under 100ml and the top is screwed on. To avoid this, I always recommend taking the pad or wipe, or solid bar versions, when possible, to prevent spillages in your backpack.

'For extra precaution, keep important items - like your passport - safe by keeping them in a clear ziplock bag to protect them from accidental spillages so they're fit to travel with.'

Don't take a hardcover suitcase

If you do take a bag for the cargo hold, Emilie warns: 'Passengers tend to think that hard-shell suitcases are more resistant than fabric ones, but it's actually the opposite. Hardcovers can get easily broken by the pressure of the other bags once they're all packed together in the hold.

'To avoid damage to your bag, I always recommend choosing a fabric suitcase as these are actually more durable. Picking one in a bright colour can help you spot your bag more quickly during baggage delivery. Just avoid white as it won't stay that colour for long!'

Emilie adds: 'Another common bag mistake people make is opting for a four-wheel suitcase. These are never as durable or reliable as a two-wheel spinner and I'd always avoid them.'

Avoid taking multiples of items

The art of the capsule wardrobe is important

Emilie says: 'If you're taking a short flight and only going for a few days, travelling with a carry-on bag or backpack can be a more practical option, helping you to avoid delays while waiting for baggage on the other side. Just make sure you've checked your booking details to make sure your bag meets the criteria before you travel.

'Pre-plan your outfits in advance to ensure only the essentials are being taken and try to avoid taking multiples of items, as this will free up some space. For example, take one pair of trainers, jeans, a jumper or cardigan and a coat. Take a few T-shirts and enough underwear and one nice dress if you know you'll be going out. Flat trainers are both practical and use less space, so bring these if you can.'

Avoid taking fresh food in your bag

Whilst it's nice to bring local delicacies back from your trip, think about whether they'll get through customs.

Emilie says: 'Food and drinks are ok to pack in your suitcase as long as they are packed well and protected from leaking. Make sure to avoid anything with a strong smell as that might attract the attention of sniffer dogs at customs. Cold meats, cheese and fresh food in general are often forbidden in international travels so make sure to keep this in mind.'

Ensure your bag is light enough to lift

While it's crucial you don't overpack to meet your bag-weight limits, Emilie adds: 'Please don't pack a bag that is too heavy. If you can't lift it and place it in the overhead compartment yourselves, it's too heavy for us attendants, too, and we don't want to injure our backs to lift your luggage.'

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Solar Storm Intensifies, Filling Skies With Northern Lights

Officials warned of potential blackouts or interference with navigation and communication systems this weekend, as well as auroras as far south as Southern California or Texas.

By Katrina Miller and Judson Jones

Katrina Miller reports on space and astronomy and Judson Jones is a meteorologist.

A dramatic blast from the sun set off the highest-level geomagnetic storm in Earth’s atmosphere on Friday that is expected to make the northern lights visible as far south as Florida and Southern California and could interfere with power grids, communications and navigations system.

It is the strongest such storm to reach Earth since Halloween of 2003. That one was strong enough to create power outages in Sweden and damage transformers in South Africa.

The effects could continue through the weekend as a steady stream of emissions from the sun continues to bombard the planet’s magnetic field.

The solar activity is so powerful that the National Oceanic and Atmospheric Administration, which monitors space weather, issued an unusual storm watch for the first time in 19 years, which was then upgraded to a warning. The agency began observing outbursts on the sun’s surface on Wednesday, with at least five heading in the direction of Earth.

“What we’re expecting over the next couple of days should be more significant than what we’ve seen certainly so far,” Mike Bettwy, the operations chief at NOAA’s Space Weather Prediction Center, said at a news conference on Friday morning.

For people in many places, the most visible part of the storm will be the northern lights, known also as auroras. But authorities and companies will also be on the lookout for the event’s effects on infrastructure, like global positioning systems, radio communications and even electrical power.

While the northern lights are most often seen in higher latitudes closer to the North Pole, people in many more parts of the world are already getting a show this weekend that could last through the early part of next week.

As Friday turned to Saturday in Europe, people across the continent described skies hued in a mottling of colors.

Alfredo Carpineti , an astrophysicist, journalist and author in North London, saw them with his husband from the rooftop of their apartment building.

“It is incredible to be able to see the aurora directly from one’s own backyard,” he said. “I was hoping to maybe catch a glimpse of green on the horizon, but it was all across the sky in both green and purple.”

Here’s what you need to know about this weekend’s solar event.

How will the storm affect people on Earth?

A geomagnetic storm watch or warning indicates that space weather may affect critical infrastructure on or orbiting near Earth. It may introduce additional current into systems, which could damage pipelines, railroad tracks and power lines.

According to Joe Llama, an astronomer at Lowell Observatory, communications that rely on high frequency radio waves, such as ham radio and commercial aviation , are most likely to suffer. That means it is unlikely that your cellphone or car radio, which depend on much higher frequency radio waves, will conk out.

Still, it is possible for blackouts to occur. As with any power outage, you can prepare by keeping your devices charged and having access to backup batteries, generators and radio.

The most notable solar storm recorded in history occurred in 1859. Known as the Carrington Event, it lasted for nearly a week, creating aurora that stretched down to Hawaii and Central America and impacting hundreds of thousands of miles of telegraph lines.

But that was technology of the 19th century, used before scientists fully understood how solar activity disrupted Earth’s atmosphere and communication systems.

“That was an extreme level event,” said Shawn Dahl, a forecaster at NOAA’s Space Weather Prediction Center. “We are not anticipating that.”

Unlike tornado watches and warnings, the target audience for NOAA’s announcements is not the public.

“For most people here on planet Earth, they won’t have to do anything,” said Rob Steenburgh, a space scientist at NOAA’s Space Weather Prediction Center.

The goal of the announcements is to give agencies and companies that operate this infrastructure time to put protection measures in place to mitigate any effects.

“If everything is working like it should, the grid will be stable and they’ll be able to go about their daily lives,” Mr. Steenburgh said.

Will I be able to see the northern lights?

It is possible that the northern lights may grace the skies this week over places that don’t usually see them. The best visibility is outside the bright lights of cities.

Clouds or stormy weather could pose a problem in some places. But if the skies are clear, even well south of where the aurora is forecast to take place, snap a picture or record a video with your cellphone. The sensor on the camera is more sensitive to the wavelengths produced by the aurora and may produce an image you can’t see with the naked eye.

Another opportunity could be viewing sunspots during the daytime, if your skies are clear. As always, do not look directly at the sun without protection. But if you still have your eclipse glasses lying around from the April 8 event, you may try to use them to try to spot the cluster of sunspots causing the activity.

How strong is the current geomagnetic storm?

Giant explosions on the surface of the sun, known as coronal mass ejections, send streams of energetic particles into space. But the sun is large, and such outbursts may not cross our planet as it travels around the star. But when these particles create a disturbance in Earth’s magnetic field, it is known as a geomagnetic storm.

NOAA classifies these storms on a “G” scale of 1 to 5, with G1 being minor and G5 being extreme. The most extreme storms can cause widespread blackouts and damage to infrastructure on Earth. Satellites may also have trouble orienting themselves or sending or receiving information during these events.

The current storm is classified as G5, or “extreme.” It is caused by a cluster of sunspots — dark, cool regions on the solar surface — that is about 16 times the diameter of Earth. The cluster is flaring and ejecting material every six to 12 hours.

“We anticipate that we’re going to get one shock after another through the weekend,” said Brent Gordon, chief of the space weather services branch at NOAA’s Space Weather Prediction Center.

Why is this happening now?

The sun’s activity ebbs and flows on an 11-year cycle, and right now, it is approaching a solar maximum. Three other severe geomagnetic storms have been observed so far in the current activity cycle, which began in December 2019, but none were predicted to cause effects strong enough on Earth to warrant a watch or warning announcement.

The cluster of sunspots generating the current storm is the largest seen in this solar cycle, NOAA officials said. They added that the activity in this cycle has outperformed initial predictions .

More flares and expulsions from this cluster are expected, but because of the sun’s rotation the cluster will be oriented in a position less likely to affect Earth. In the coming weeks, the sunspots may appear again on the left side of the sun, but it is difficult for scientists to predict whether this will cause another bout of activity.

“Usually, these don’t come around packing as much of a punch as they did originally,” Mr. Dahl said. “But time will tell on that.”

Jonathan O’Callaghan contributed reporting from London.

An earlier version of this article misstated the radio frequencies used by cellphones and car radios. They are higher frequencies, not low.

How we handle corrections

Katrina Miller is a science reporting fellow for The Times. She recently earned her Ph.D. in particle physics from the University of Chicago. More about Katrina Miller

Judson Jones is a meteorologist and reporter for The Times who forecasts and covers extreme weather. More about Judson Jones

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• Diversity, Equity & Inclusion at Delta
• Racial and Ethnic Diversity
• LGBTQ+ Diversity
• People with Disabilities
• Veterans and the Military
• Sustainability
• Awards & Recognition
• Global Partners

Delta Air Lines has been named an honoree of The Civic 50 by  Points of Light , the world’s largest nonprofit dedicated to corporate volunteerism, for the seventh year in a row. The award recognizes Delta as one of the 50 most community-minded companies in the United States. Delta was also recognized as this year’s Industrials Sector Leader for the second year in a row and received high marks on the Integration category, showcasing that Delta’s community engagement programs are well integrated across all business functions, propelling our work and service to communities.  

“Delta is proud to be recognized as an honoree of The Civic 50 for the seventh year in a row," said Tad Hutcheson, Managing Director of Community Engagement at Delta. "Giving back has been core to the Delta culture for nearly 100 years. Our Delta employees and volunteers are a driving force for positive change in communities where we live, work and serve. We remain committed to connecting communities and caring for the planet and the people within it."   

For more than a decade, The Civic 50 has served as the standard for corporate citizenship and showcases how leading companies are moving social impact and community to the core of their business. The Civic 50 honorees are companies with annual U.S. revenues of at least $1 billion and are selected based on four dimensions of their corporate citizenship and social impact programs: investment of resources, integration across business functions, institutionalization through policies and systems and impact measurement. 

“Expectations for companies to be leaders in civic engagement continue to increase,” said Jennifer Sirangelo, President and CEO, Points of Light. “Delta Air Lines demonstrates how to maximize the full range of their assets – from people power to policy to financial contributions – to meet pressing needs and create thriving communities where they live and work. We’re thrilled to uplift and celebrate them as an honoree of The Civic 50 2024.” 

The Civic 50 sets the standard for corporate civic engagement and creates a roadmap for companies seeking to best use their time, talent and resources to improve the quality of life in the communities where they do business. 

The Civic 50 survey is administered by True Impact and consists of quantitative and multiple-choice questions that inform scoring process. The Civic 50 is the only survey and ranking system that exclusively measures corporate community engagement. To view the full report and see the full list of The Civic 50 honorees for 2024, visit the Points of Life website . 

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