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Astronomy

Light-Year

Quick fact

One light-year is roughly 9.46 trillion kilometers — that's about 6 trillion miles. The nearest star beyond the Sun, Proxima Centauri, is 4.24 light-years away.

Why this is interesting

When you look at the stars, you're looking back in time. But just how far back can we see? The answer begins with a simple question: what is a light-year?