On a dark night you can see the Andromeda galaxy with your bare eyes. That light set off around 2.5 million years ago, before our species walked the Earth.
Truth label: Established. Strong evidence and broad agreement among experts.
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Looking is time travel
Everything you see in the night sky is a view of the past. The further away, the older the picture.
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- Light takes time. Light travels about 300,000 km every second. Across the vastness of space, that still adds up to millions of years.
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Roughly how old is the Andromeda light you can see tonight?
2.5 million years. Andromeda is about 2.5 million light years away.
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