Earth & Space
14 breaks
Planets, weather, oceans and the sky above them.
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Why Mars sometimes walks backwards across the sky
Every 26 months or so, Mars slows down, stops, and drifts backwards against the stars for a couple of months before carrying on. Ancient astronomers built…
Why we only ever see one side of the Moon
The Moon always shows us the same face, so it's easy to assume it doesn't spin. It does. It turns exactly once for every orbit, about every 27.3 days, so the…