For instance, the sun is more than 8 light-minutes from Earth, while the moon is just over a light-second away. Like degrees, the light-year can also be broken down into smaller units of light-hours, light-minutes or light-seconds.
The galaxy GN-z11 is thought to be the farthest detectable galaxy from Earth at 13.4 billion light-years away. Some of the most distant galaxies we can see are billions of light-years from us. The nearest spiral galaxy to ours, the Andromeda galaxy, is 2.5 million light-years away.
The center of our galaxy is about 27,000 light-years away. 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. Measuring in miles or kilometers at an astronomical scale is impractical given the scale of figures being used. One estimate puts the diameter of the known universe at 28 billion light-years in diameter.
At first glance, this may seem like an extreme distance, but the enormous scale of the universe dwarfs this length. To find the distance of a light-year, you multiply this speed by the number of hours in a year (8,766). The speed of light is constant throughout the universe and is known to high precision. 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. 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. On the scale of the universe, measuring distances in miles or kilometers is cumbersome given the exceedingly large numbers being discussed.
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