An amateur astronomer has identified a previously unknown small moon orbiting Jupiter, using data from the Canada-France-Hawaii Telescope captured in February 2003. This object belongs to the Carme group, a cluster of retrograde satellites around the gas giant.
Just four years ago, Jupiter was known to have 67 moons. By 2018, astronomers confirmed 12 more, raising the total to 79 Jovian moons. Like other prograde moons (rotating in the same direction as the planet), these receive names ending in "a"; retrograde ones end in "e." Recent additions honor Zeus's descendants, including Pandia, Ersa, Eirene, Philophrosyne, and Eupheme.
Jupiter's powerful magnetic field traps space debris, suggesting it may harbor tens or even hundreds of undiscovered moons. Enter Kai Ly, an amateur astronomer whose keen analysis spotted one—marking the first such discovery by an amateur.
This tiny moon joins the Carme group, sharing similar retrograde orbits with semi-major axes between 22,900,000 and 24,100,000 km. These satellites travel in the opposite direction to Jupiter's rotation, on highly inclined paths relative to the planet's orbital plane.
Carme, the group's largest at about 46 km in diameter, is believed to be a captured asteroid. The other 22 members are likely fragments from a collision.
Ly made the find while sifting through 2003 datasets from University of Hawaii researchers using the Canada-France-Hawaii Telescope (CFHT). He focused on February observations, when Jupiter was at opposition—perfectly aligned with Earth and the Sun for optimal viewing of the Jovian system.
Follow-up data from Hawaii's Subaru Telescope confirmed the object's gravitational bond to Jupiter. Ly called it "a summer hobby before returning to school."
Designated temporarily as EJc0061, this 80th moon of Jupiter awaits official naming by the International Astronomical Union. Its retrograde path ensures a name ending in "e."
