Starfish don't have brains, and yet they're able to mobilize hundreds of tiny hydraulic tube feet to get around. Now scientists are getting an understanding of just how they do that.

PLUS:

• Atmospheric pollution from an individual rocket re-entry event measured for the first time
• How the Earth’s greenhouse age transitioned into a world with frozen poles
• What is dark matter? The contenders — from WIMPs to dark matter stars
• Quirks Question: why doesn’t flowing water freeze at the same temperature as still water?

(Correction: A previous version of the dark matter story referred to a study published last fall that mapped the distribution of dark matter, but the study was published on Jan. 26, 2026.)