Understanding what a light year truly represents can change your perspective on space and time. It’s a unit that measures the incredible distance light covers in a single Earth year.
To compute this distance, astronomers multiply the speed of light, which is always constant at 186,000 miles per second, by the number of seconds in a year. One light year equals approximately 6 trillion miles or 10 trillion kilometers.
How far is a light year?
A light year is about 6 trillion miles (9.7 trillion kilometers). In contrast, the distance from Earth to the sun is roughly 93 million miles (150 million kilometers). So, traveling from Earth to the sun covers much less distance than a light year.
Of course, visualizing such a vast distance can be challenging, especially since we’re used to thinking in terms of years and our planet. To put this into perspective, consider other objects within one light-year of Earth. The nearest star, apart from our sun, is Proxima Centauri, which is roughly 4.2 light-years away. In contrast, the farthest object we’ve observed, a galaxy named GN-z11, is over 32 billion light-years away!
Why do we measure in light years?
Light is constant, and using light years measures distance accurately within our galaxy and others. One light year may sound like a lot, but it’s actually a small unit given the vastness of space.
Using kilometers or miles to measure distant objects isn’t useful. For instance, measuring an interstellar object’s distance in miles or kilometers is nearly impossible. Light years make it easier to compare and understand distances in space. Although one light year might not seem significant daily, it is incredibly important for astronomers to explore the universe!