Tidally-locked Valentine

Illustration of a tidally-locked planet.
February 14, 2017
CreditNASA-JPL/Richard Barkus
  • english

Tidally-locked planets are so close to their star, their star's gravity holds them in place like Earth holds the moon. One side of a tidally-locked planet always faces its star, and one side always faces away. That gives one-half of the planet a sunny day side, and the other half a lasting starry night.