Astronomers Accidentally Discover 12 New Moons Orbiting Jupiter


The discovery of a dozen new moons circling Jupiter has been reported by a team of astronomers. After this discovery, the count of Jupiter’s moons has reached 79 from 67, most for any planet. While looking for objects on the fringes of the solar system, astronomers spotted these tiny moons near Jupiter which was unintentional and unplanned. One of the 12 moons is also called an ‘oddball’ due to its unusual orbit.

Jupiter’s diameter is 88,846 miles, i.e. 142, 984 km. It is home to Ganymede, the biggest moon in the solar system, having a diameter of 3,273 miles (5,268 km). However, the new small ones are tinier. The size range is about six-tenths of a mile (1 km) to 2.5 miles (4 km). Researchers concluded that these moons may have been formed near Jupiter during the early days of the solar system and were probably captured by Jupiter’s strong gravitational pull.

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

Astronomers group Jupiter’s moons by their distance from the planet as well as their orbital direction. If a moon circles in the same direction as a planet’s rotation, that moon’s orbit is called prograde. If moon circles a planet in the opposite direction of a rotating planet, that orbit is retrograde. Most moons, including Earth’s, have prograde orbits. Two of the newly discovered moons, the ones closest to Jupiter, have prograde orbits, too.

The most interesting of the new moons is Valetudo, named after the ancient Roman god Jupiter’s great-granddaughter, the goddess of health and hygiene. Valetudo orbits Jupiter in the same direction that the planet spins, but a bunch of other small moons share the same orbital path while travelling in the opposite direction. Jupiter’s 79 known moons are the most of any planet in the solar system, followed by the 62 identified around the giant ringed gas planet Saturn.

A moon is defined as any object, regardless of size that orbits a planet, not the Sun. Only the two innermost planets in the solar system, Mercury and Venus, have none. The astronomers do not know the composition of the dozen newly identified moons. They could be rock, ice or a mixture.