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Astronomers using ground-based telescopes have identified two more moon circling Jupiter, bringing its total now to 69.
Both of these discoveries, as with the vast majority of Jupiter’s moons, occupy retrograde orbits, with inclinations greater than 90°, meaning that they move in directions opposite that of the planet’s spin. These distant, irregular orbits imply that these bodies formed elsewhere in the outer solar system and were captured while passing by early in the planet’s history.
A number of the moons recently discovered have since been lost because their orbits were too poorly constrained. However, some of these lost moons have also be recovered.