Published: Tue, July 17, 2018
Science | By Joan Schultz

Astronomers find 12 new moons orbiting Jupiter, including an "oddball"


Due to their sizes - just 0.6 to 1.9 miles (1 to 3km) in diameter - these moons are more influenced by surrounding gas and dust.

The number of known objects orbiting Jupiter is now 79, the most of any planet in the solar system. The orbits of the new moons are marked with thicker curves.

Sheppard, Chad Trujillo of Northern Arizona University and David Tholen of the University of Hawaii are on a quest to find as many faint, distant objects on the edge of the solar system as they can.

"This is an unstable situation", Sheppard said.

But cosmic serendipity placed the moons in front of their telescope.

Using the Blanco four-metre telescope at Cerro Tololo Inter-American in Chile - which had been recently fitted with a new and highly sensitive instrument called the "Dark Energy Camera", which is about the size of a small vehicle - they detected objects that seemed to be moving against the background stars. It moved in the prograde motion together with Jupiter and then collided with another object, causing the smaller retrograde-moving moons. "Maybe a dwarf moon for anything that's 1 kilometer in size of smaller", he says. Because the planet is so big and bright, researchers surmised that unrecorded moons could be faint, or even obscured, or quite far from the gas giant. These regular satellites consist of an inner group of four moons that orbit very closely to the planet and a main group of four Galilean moons that are Jupiter's largest moons.

The moon, which has the proposed name Valetudo, orbits in the same direction as Jupiter's rotation, unlike all the other moons in the outer group.

The moon we see today is the remainder of a much bigger world that blew apart after the crashes.

It's been nicknamed Valetudo after the Roman goddess of health and hygiene who is the great-granddaughter of the god Jupiter.

"It takes several observations to confirm an object actually orbits around Jupiter", Gareth Williams at the International Astronomical Union's Minor Planet Center, said in a statement.

But he said he expects astronomers will discover more tiny moons in the coming decades.

This new "oddball" moon is more distant and more inclined than the prograde group of moons and takes about one and a half years to orbit Jupiter.

"Valetudo is like driving down the highway on the wrong side of the road", said Sheppard.

A team led by Scott S. Sheppard, of the Carnegie Institution for Science, spotted the moons while hunting for a possible massive planet, known as "planet X" far beyond Pluto.

And he thinks Jupiter might have even more moons just as small waiting to be found. TheyÂre calling one moon an ‘oddball because of its unusual orbit. That means the revolve around Jupiter opposite from the planet's rotation. Many of Jupiter's outer moons were likely formed by collisions between larger retrograde moons and oddball prograde satellites. If moon circles a planet in the opposite direction of a rotating planet, that orbit is retrograde.

The team also discovered one particularly odd moon in the new batch.

But the last moon is a weird one.

The other nine moons, grouped in clusters of three, have retrograde orbits.

"Jupiter was well-placed in the sky to kill two birds with one stone", Sheppard said. Currently, the research team is running models to determine how long it will take to happen.

Valetudo is something of an oddball. Instead, scientists will have to wait for a future spacecraft, either flying past Jupiter or orbiting it.

It has a prograde orbit but is more distant and at a different incline.

The astronomers were not intentionally searching for new Jovian moons when they began observing. They could be rock, ice or a mixture.

Jupiter, the fifth planet from the Sun, has a diameter of 142,984km. This matter became part of the planets themselves.

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