California’s Cliffs Are Collapsing One by One
Researchers are stepping up their efforts to understand why—and when—bluffs come crashing down.
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Josh Edelson / AFP / Getty The Ripple Effects of a Space Skirmish
If a conflict breaks out between countries with weapons in orbit, it could threaten space access for everyone.
Prakash Singh / AFP / Getty Is Planet Nine Even Real?
A year and a half after it was proposed, astronomers are still debating whether the giant mystery planet actually exists.
ESO / Tom Ruen / nagualdesign
