Astronomers have discovered that Earth will temporarily capture an asteroid, 2024 PT5, starting Sunday. This “mini-moon,” about 33 feet wide, will orbit Earth once before departing on Nov. 25 to continue its solar orbit. Discovered in August via a NASA-funded system and a South African observatory, the asteroid is too small and dim to be seen with the naked eye or amateur telescopes. Earth’s permanent moon formed 4.5 billion years ago, and the solar system hosts nearly 300 moons, mostly around Saturn and Jupiter.