One of the new moons was described as a "real oddball" by researcher Scott Sheppard at the Carnegie Institution for Science, because of its tiny size, it measuring just about a half-mile (one kilometer) across.

It also "has an orbit like no other known Jovian moon" and is "likely Jupiter's smallest known moon," he added.

This oddball takes about a year and a half to circle Jupiter, and orbits at an inclined angle that crosses paths with a swarm of moons traveling in a retrograde, or in the opposite direction of Jupiter's spin rotation.

"This is an unstable situation," said Sheppard.

"Head-on collisions would quickly break apart and grind the objects down to dust."

The oddball moon, along with two other new moon discoveries, orbit in the prograde, or same direction as the planet's rotation.

The inner moons take about a year to circle Jupiter, while the outer moons take twice as long.

All the moons may be fragments that broke apart when their larger, parent cosmic bodies collided.

Astronomers have proposed the name "Valetudo" for the oddball moon, after the Roman god Jupiter's great-granddaughter, the goddess of health and hygiene.

The Italian astronomer Galileo Galilei discovered the first four of Jupiter's moons in 1610.

The current team of astronomers did not set out to find new moons of Jupiter, but was scanning the skies for planets beyond Pluto when the moons fell into the path of their telescope.

The new moons were first glimpsed in 2017, using a telescope based in Chile and operated by the National Optical Astronomical Observatory of the United States.

It took a year for their orbits to be confirmed with a series of other telescopes in the United States and Chile.