Learned about Zoozve today, which is a quasi-moon of Venus. A quasi-moon is one that appears to orbit a planet, but it doesn’t actually orbit that planet. Zoozve is the first-ever identified quasi-moon in our solar system.

Radiolab

LULU: So Zoozve is, like, in a poly relationship with the Sun and Venus?

LATIF: Yeah, which by the way, nobody has ever seen before.

PAUL WIEGERT: Revealing, if you will, the first quasi-moon known in our solar system.

LULU: “Quasi” meaning just like a small moon?

LATIF: “Quasi” meaning neither moon nor not moon. It’s this mysterious in-between thing that’s the first anyone has ever discovered anywhere in the universe.

Radiolab

LATIF: Sure. There are rules, there are definitely rules. But the thing is, Zoozve is following rules that we can never fully grasp. It’s a three-way dancer, not a two-way dancer, so it’s not on those predictable rails. And because of its polyamorous relationship with the Sun and Venus, it actually presents sort of a mathematical conundrum known as the three body problem.

physics.uwo.ca

Though quasi-satellites remain close to their planet compared with other 1:1 resonant orbits like Trojans, they should not be confused with traditional satellite orbits. “A traditional moon or satellite orbits a planet,” said Dr. Wiegert. “Quasi-satellites are properly said to orbit the Sun, and though their path takes them around a planet, their behavior is very different from that of ordinary moons”. The distinction between satellites and quasi-satellites arises because quasi-satellites are too far from their planet for it’s gravity to exert a significant hold on them, though the planets do play a role in the stability of quasi-satellites.