There Was a Planet That Swallowed a Moon

What if Venus once had a moon, and then destroyed it?

A new study suggests that under plausible conditions, an ancient Venusian moon could have slowly migrated inward, crossed the Roche limit and ultimately been torn apart or swallowed by the planet. And Venus may not be the only hungry object in our cosmic neighborhood: another recent study explores whether the young Sun could have consumed a super-Earth, leaving subtle chemical and structural fingerprints behind billions of years later.

This week on Star Trails, we're following a cosmic version of the old nursery rhyme "There Was an Old Lady Who Swallowed a Fly." Planets can swallow moons. Stars can swallow planets. Galaxies devour other galaxies. Along the way, we'll explore why orbits aren't permanent, why Earth's Moon is slowly escaping us while Mars's Phobos is falling inward, and how gravity can transform apparently stable systems over astronomical timescales.

Then in the Night Sky Report for September 27 through October 3, autumn has officially arrived. We'll look for Saturn near opposition, a Moon-and-Pleiades pairing, Jupiter and its Galilean moons, and the changing fall sky. We'll also visit a newly discovered crater on the Moon and check in on the fast-moving mystery of Webb's strange Little Red Dots.

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