Since the universe is so big, astronomers don’t measure distances in miles or kilometers. Instead, they use light years and other astronomical measurements to determine the distances between objects in space.
If, however, you’re not scientifically minded, it can be helpful to use a unit of measurement you’re familiar with to give some context. Doing so can enable you to truly comprehend the vastness of space.
This is the reason why we’ve written this article, which explains how far away a light year is in miles and how long it would take to walk that distance. We’ll also explain exactly what a light year is and give some additional information on light years that you might find interesting.
The fastest-moving thing in our universe is light, which travels at 670,616,629 miles per hour (or 1,079,252,849 kilometers per hour) in a vacuum.
The distance of a light year in miles can be worked out by multiplying this speed by 8,766 (which is the number of hours in a year) to get 5,878,625,370,000 miles or 9.5 trillion kilometers.
Continue reading to find out more about light years and gain a better understanding of just how big the universe is.
Because of the word “year,” you’d be forgiven for thinking that a light year is a unit of time. But it is, in fact, a measurement of distance.
A light year is the distance that light travels in a single Earth year (364.25 days or 8,766 hours), which, as stated above, is about 6.7 trillion miles or ten trillion kilometers.
But rather than discussing the universe using excessively large numbers like these, scientists measure the distances between Earth and space objects outside our solar system in the time it takes light to travel across that expanse. For example, one of the nearest stars to us after the sun (Sirius) is 8.611 light years away, meaning the light we can see from the star takes just over eight-and-a-half years to reach us.
Because it takes time for the light to reach us, what we are seeing in the night sky has already happened and we are actually looking back in time. The farthest planet from Earth that we can see with the naked eye is Saturn, which is 0.00015 light years away. This means the light from Saturn takes around 80 minutes to reach our eyes. So, if the planet were destroyed by an asteroid while you were looking at it, you would be able to see it for about 80 minutes after it had been destroyed.
The oldest view of our universe is the cosmic microwave background (CMB). This is the most distant object astronomers can see with a telescope, occurring 13.8 billion years ago, just after the Big Bang. This is the reason why the telescope is sometimes called an “astronomical time machine”.
If you walked a mile every 20 minutes and didn’t stop for any breaks, it would take around 225 million years to walk a light year. Although, you wouldn’t be rewarded at the end of your walk, as the closest star to earth, Proxima Centauri, is more than four light-years away.
Another way to comprehend the vastness of the universe is to consider how long it would take to get to one of the most distant exoplanets (a planet that orbits a star outside the solar system) in our galaxy (Kepler-443b). The answer is 28 billion years — but that’s only if you were driving a car at 60 miles per hour! And even if you traveled at light speed, it would still take about 3,000 years.
Given the scale of the figures we’re talking about, it’s impractical to measure the distances to the other galaxies, bright stars, and star clusters in our universe in miles. With that in mind, here’s how many light years away they are:
- The Orion Nebula — The closest star-forming region to Earth is 1,300 light years away (that’s 7,861,000,000,000,000 miles, in case you’re interested)
- Andromeda galaxy — The nearest spiral galaxy to ours is 2.5 million light years away
- GN-z11 galaxy — Some of our most distant galaxies (that we can see) are billions of light years away from us, with the farthest — the GN-z11 galaxy — 13.4 billion light years away
- The center of The Milky Way — The center of our own galaxy is around 27,000 light years away
- Alpha Centauri — This triple star system is 4.367 light years from us
- Sirius — One of the nearest stars to us after the sun is 8.611 light years away
- Vega — The brightest star in the northern constellation of Lyra is 25.05 light years from the Earth
- Pleiades — The open star cluster of Pleiades is 444.2 light years away
- Antares — This red supergiant star is 554.5 light years away from us
- Hercules — Also known as M13, this globular star cluster is around 402 light years from Earth
- Sombrero galaxy — Sometimes referred to as M104, this galaxy is about 29 million light years away
- Whirlpool galaxy — The Whirlpool galaxy, also known as M51, is 31 million light years from Earth
How many light years away is the moon?
The distance between the Earth and the moon is about 4.063x10-11 light years.
How many light years away is the sun?
The sun is roughly 1.578x10-5 light years away from Earth.
How many light years away is Mars?
The distance between Earth and Mars varies since they both orbit the sun. At each point in their orbits, the distance between them will be different. At their furthest apart, the distance between Earth and Mars is about 4.228x10-5 light years. At their closest, the distance in light years is about 5.813x10-6.
How many light years away is Jupiter?
The distance between Earth and Jupiter varies since they both orbit the sun. At each point in their orbits, the distance between them will be different. At their furthest apart, the distance between Earth and Jupiter is about 1.023x10-4 light years. At their closest, the distance in light years is about 6.215x10-5.
How many light years away is Pluto?
The distance between Earth and Pluto varies since they both orbit the sun. At each point in their orbits, the distance between them will be different. At their furthest apart, the distance between Earth and Pluto is about 7.928x10-4 light years. At their closest, the distance in light years is about 2.812x10-4.
A light year can be broken down into smaller units of measurement. These are light hours, light minutes, and light seconds.
These measurements are used by scientists when they’re talking about communications with rovers or deep-space satellites.
To give you an idea of these distances, it might be helpful to know that the sun is about eight light minutes from the Earth, while the moon is just over a light second. A light second is 7.5 times the distance around the equator of the Earth. This means that if you could travel at the speed of light, you would be able to circle the Earth’s equator seven-and-a-half times in just one second.
In addition to light years, astronomers use other units of measurement to determine the distance between different objects in space. While light years and parsecs are used to measure distances between objects outside of our solar system, astronomical units and lunar distance are used to measure distances within our solar system.
What is an Astronomical unit (AU)?
An astronomical unit is roughly the distance from the Earth to the sun. It’s the equivalent of 93 million miles, 150 million kilometers, or 8.3 light minutes.
What is Lunar distance (LD)?
Also known as ‘Earth-moon characteristic distance’, lunar distance is the distance from the Earth to the moon. It is roughly 250,000 miles, 400,000 kilometers, or 1.28 light seconds.
What is a Parsec (pc)?
Like light years, parsecs are used to measure distances between space objects outside of our solar system, meaning it is a much larger unit of measurement. A parsec equals about 19.2 trillion miles, 30.9 trillion kilometers, 206,000 astronomical units, or 3.26 light years.
The universe is vast, which is why astronomers use light years and other astronomical measurements to determine the distances between space objects. However, to truly comprehend the vastness of space, it can be helpful to know what the equivalent of a light year is in miles and kilometers. One light year is equal to 5,878,625,370,000 miles, which is 9.5 trillion kilometers, but this might not mean a great deal without adding some context: If you walked a mile every 20 minutes and didn’t stop for any breaks, it would take around 225 million years to walk a light year. Or, to get to one of the most distant exoplanets in our galaxy, it would take 28 billion years — but that’s only if you were driving a car at 60 miles per hour. And even if you traveled at light speed, it would still take you about 3,000 years. One of the nearest stars to us after the sun is 8.611 light years away, while the farthest galaxy that we know of is 13.4 billion light years away.
Light years can be broken down into light hours, light minutes, and light seconds. To give you an idea of these distances, the sun is about eight light minutes from the Earth, while the moon is just over a light second. Astronomers also use astronomical units and lunar distance to measure distances within our solar system, and parsecs are used to measure distances between space objects outside our solar system.