In 2014, this same team found the object with the most-distant known orbit in our Solar System and was the first to realize that an unknown massive planet at the fringes of our Solar System, far beyond Pluto, could explain the similarity of the orbits of several small extremely distant objects.
But cosmic serendipity placed the moons in front of their telescope. In their review was the Jupiter.
That seems to be what happened to astronomers working at the Cerro Tololo Inter-American Observatory in Chile, where a planned survey of trans-Neptunian objects was interrupted by Jupiter. The orbits of 9 other small Jovian moons are yet unknown.
Europa, one of Jupiter's larger moons, casts a shadow on the planet's surface. Galileo discovered the first four of Jupiter's moons, all huge, in 1610. The largest Galilean moon, Ganymede, is bigger than the planet Mercury. They saw a new group of objects moving around the giant gas planet but didn't know whether they were moons or asteroids passing near Jupiter.
The twelfth moon has already earned a proposed name, despite being only about two-thirds of a mile in diameter. He and his colleagues announced the discovery on 17 July. That's because Valetudo, named for the Roman goddess of health and hygiene, is a true oddball. They are about one to two kilometers (miles) across, said astronomer Gareth Williams of the International Astronomical Union's Minor Planet Center.
Because Jupiter is also a bright planet, astronomers have had to deal with the issue of glare and scattered light affecting the space where moons can exist.
The finding brings the total number of known moons of Jupiter to a whopping 79.
Size isn't a requirement to be a moon - there's no such thing as a dwarf moon.
The tiny moon's orbit takes it both inside and outside of where the other new moons orbit, putting it at a high risk of colliding with them. Because of that small moon's orbit, it may be eventually be destined for an crash.
Astronomers Discover Twelve New Jovian Moons | Astronomy
Eleven are "normal" outer moons, but the 12th, thought to be less than 1km in diameter, has been termed an "oddball" due to its curious orbit. They were looking for Planet Nine. While the retrograde moons orbit in a clockwise direction, Valetudo travels in a counter-clockwise direction.
None of the dozen moons is more than a couple of miles across.
"Our other discovery is a real oddball and has an orbit like no other known Jovian moon", Sheppard said. This swarm may have originally been three separate moons that broke apart after collisions.
The team said the likelihood is that the peculiar moon could be the last remnants of a once-larger group of prograde-orbiting moon that would have formed some of the retrograde moon groupings during previous head-on collisions. In fact, of Jupiter's 67 previously discovered moons, the 33 outermost moons all have retrograde orbits.
Valetudo is something of an oddball.
It has a prograde orbit but is more distant and at a different incline. The stage is set, in other words, for possible moon-moon collisions.
The team also discovered one particularly odd moon in the new batch. They could be rock, ice or a mixture. Sheppard said. "That is what we are trying to answer". Uranus and Neptune are in the row with 27 and 14 moons respectively, according to the current space information. This matter became part of the planets themselves.
Which could explain the theory that this wee moon is the final dregs of a once-larger prograde-orbiting satellite, corroded over time by bumps and scrapes with other celestial bodies.
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