Astronomy Picture of the Day

Earth's Gravity May Have Kept the Early Moon's Volcanic Heart Beating
Posted on: 6 Nov 2026

We typically think of the Moon as a static, floating object that has remained the same for basically its entire lifetime, with an occasional asteroid impact serving as an exception. That understanding is grounded in physics - the Moon should have cooled rapidly after forming when a huge protoplanet hit the early Earth around 4.5 billion years ago. But, some lunar material returned from the Chang’e-5 mission was notably formed only around two billion years ago, yet appeared to be volcanic in origin. So how did a world that was supposed to have settled down without volcanism remain hot enough to create these materials more than two billion years after its violent birth? A new paper from Miao Chen of the Chengdu University of Technology and his colleagues, and recently published in the journal Planet, offers an explanation - tidal heating.

'Big Bang' Fix Puts Voyager Across the 'One Light-Day' Mark
Posted on: 6 Nov 2026

Flashback to 1977. Jimmy Carter was U.S. president, Star Wars was a box office hit, and the two Voyager spacecraft departed on an historic Grand Tour of the solar system. Now, teams at NASA’s Jet Propulsion Laboratory are working to keep the missions active, as they push the boundaries of interstellar space beyond the solar system.