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An picture of far-off galaxies captured by the buzzpatterson.com/ESA Hubble an are Telescope. Credit: ESA/Hubble & buzzpatterson.com, RELICS; Acknowledgment: D. Coe et al.

You are watching: How far away is a light year


For most an are objects, we use light-years to describe their distance. A light-year is the distance light travels in one planet year. One light-year is around 6 trillion miles (9 trillion km). The is a 6 with 12 zeros behind it!

Looking ago in Time

When us use powerful telescopes come look at far-off objects in space, we space actually looking back in time. How deserve to this be?

Light travels at a rate of 186,000 mile (or 300,000 km) per second. This appears really fast, however objects in an are are so far away the it bring away a lot of time for your light to reach us. The farther an item is, the farther in the previous we view it.

Our sunlight is the closestly star to us. It is around 93 million mile away. So, the Sun"s irradiate takes around 8.3 minute to reach us. This means that we always see the sunlight as it was about 8.3 minutes ago.

The next closest star to us is around 4.3 light-years away. So, once we check out this star today, we’re in reality seeing it together it to be 4.3 years ago. Every one of the various other stars we have the right to see through our eyes are farther, some even thousands that light-years away.

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Stars are uncovered in big groups referred to as galaxies. A galaxy have the right to have millions or billions that stars. The nearest large galaxy come us, Andromeda, is 2.5 million light-years away. So, we view Andromeda as it to be 2.5 million years in the past. The universe is filled with billions of galaxies, all farther away than this. Several of these galaxies are lot farther away.


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An image of the Andromeda galaxy, as watched by buzzpatterson.com"s GALEX observatory. Credit: buzzpatterson.com/JPL-Caltech


In 2016, buzzpatterson.com"s Hubble room Telescope looked at the the furthest galaxy ever before seen, called GN-z11. The is 13.4 billion light-years away, so now we have the right to see it together it was 13.4 billion years ago. The is just 400 million year after the big bang. It is among the very first galaxies ever formed in the universe.

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Learning about the very an initial galaxies that formed after the huge bang, prefer this one, helps us know what the beforehand universe was like.


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This snapshot shows hundreds of an extremely old and distant galaxies. The oldest one uncovered so far in GN-z11 (shown in the close up image). The image is a little bit blurry since this galaxy is so far away. Credit: buzzpatterson.com, ESA, P. Oesch (Yale University), G. Brammer (STScI), P. Van Dokkum (Yale University), and also G. Illingworth (University the California, Santa Cruz)