00:00What's the farthest thing you can see with the naked eye?
00:04It's not a star.
00:05It's an entire galaxy.
00:06The Andromeda galaxy, 2.5 million light years away.
00:10To put that in perspective, one light year is about 5.9 trillion miles.
00:16So that faint smudge is nearly 15 quintillion miles away.
00:21Want to find it?
00:21Look for Cassiopeia, the sideways W, then trace your way toward Andromeda.
00:26And here's what makes this even more out of this world.
00:30Light takes time to travel.
00:32So when you look into space, you're looking back in time.
00:35Take Regulus, the brightest star in Leo.
00:38Its light takes about 80 years to reach us.
00:40You're seeing it as it was in the 1940s.
00:43And just like that, the night sky becomes a timeline.
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