Earth's "second moon" isn't quite that, but it's likely a chunk of our Moon

Kamoʻoalewa, "wobbling celestial object" in Hawaiian, is the name of a 165-foot rock that swings around the Earth on the reg, sometimes just 9 million miles from us. It's easy to think of Kamoʻoalewa as a second moon but there's one big difference: Our Moon orbits the Earth, but even though Kamoʻoalewa gets (kinda) close to us, it's actually circumnavigating the sun just as we do. According to the New York Times, it's one of four nearby "quasi-satellites" but has the most stable orbit of them. New research from University of Central Florida scientists suggests that Kamoʻoalewa may actually have been a part of our moon that was chipped off during a massive collision. From New York Times:

"The only way to be sure is to send a spacecraft to this small body," said Paul Byrne, a planetary scientist at Washington University in St. Louis who was not involved with the study. As it so happens, China's space agency plans to land on it and collect samples for return to Earth later this decade.

"Until then, we're left with the possibility that, on our journey through space, we're accompanied by the remains of a collision that punched a hole in the moon," Dr. Byrne said. "And that's pretty cool."