Lucky discovery of distant dozen puts Jupiter’s moons at 79

Astronomers have announced the discovery of a dozen more moons orbiting our solar system’s oldest and biggest planet, Jupiter.

The International Astronomical Union’s Minor Planet Centre yesterday published the orbits for 12 newfound Jovian moons — bringing Jupiter’s total to 79 moons, said Scott Sheppard, a scientist at the Carnegie Institution for Science in Washington.

Sheppard did not set out to detect new moons. His team at Carnegie, along with collaborators at the University of Hawaii and Northern Arizona University, was hunting for objects far beyond Pluto.

“We’re looking for new possible planets and dwarf planets in our solar system, just seeing what is out there,” Sheppard said.

But cosmic serendipity placed the moons in front of their telescope. During their survey in March 2017, the astronomers realised that Jupiter had moved into their field of view. The Blanco 4m telescope, at the Cerro Tololo Inter-American Observatory in Chile, is equipped with a camera able to spot faint objects. This proved to be helpful, as the unknown moons around Jupiter are small and dim.

Jupiter’s moons range in size from shrimpy satellites to whopping space hulks. Galileo discovered the first four of Jupiter’s moons, all huge, in 1610.

The moons Sheppard spied are farther-flung and tiny, each no more than 3.2km in diameter.