[ad_1]
The oldest and largest planet in our solar system, Jupiter, has many moons. And astronomers are coming to announce the discovery of a dozen or so others.
On Tuesday, the Center of the Minor Planet of the International Astronomical Union released the orbits of 12 Jovian moons – bringing the total Jupiter to 79 moons, said Scott Sheppard, a scientist. The Carnegie Institute for Science in Washington
Sheppard did not undertake to detect new moons. His team at Carnegie, along with collaborators from the University of Hawaii and the University of North Arizona, were looking for objects far beyond Pluto
"We we are looking for new planets and dwarf planets in our solar system. "But the cosmic serendipity placed the moons in front of their telescopes. During their investigation in March 2017, astronomers realized that Jupiter had moved in their field of vision. The four-meter Blanco telescope, at the Inter-American Observatory Cerro Tololo in Chile, is equipped with a camera capable of spotting very weak objects. This has proved very useful because the unknown moons around Jupiter are small and dark.
"We were able to go a little lower than anyone else could in the past," says Sheppard, "and that's why we were able to find these new moons. "
Jupiter's moons vary in size, from shrimp satellites to huge carcbades of space. Galileo discovered the first four moons of Jupiter, all enormous, in 1610. The largest Galilean moon, Ganymede, is larger than the planet Mercury. These moons are in orbit around Jupiter and travel in the same direction as the planet turns.
The spotted Sheppard moons are farther and farther apart, each no more than two miles in diameter. A moon detected by Sheppard and his colleagues is the smallest Jovian moon ever discovered. They called Valetudo, after a daughter of Jupiter and the Roman goddess of hygiene and personal health.
Gareth Williams, astronomer at the Harvard-Smithsonian Center for Astrophysics and director of the Minor Planet Center of the International Astronomical Union, predicted that around Jupiter there is no more large undiscovered objects.
But he said that he expects astronomers to discover smaller moons in the coming decades. As for the number of satellites orbiting Jupiter, Williams says he's dreading "to think how many objects are in the 100-meter range."
Size is not a requirement to be a moon – there is no dwarf moon. Not yet anyway. "Currently, the only definition of the moon is something that orbits the planet," says Sheppard, as long as it's not human.
Astronomers group the moons of Jupiter by their distance to the planet and their orbital direction. If a moon rotates in the same direction as the rotation of a planet, the orbit of this moon is called prograde. If the moon rotates around a planet in the opposite direction of a rotating planet, this orbit is retrograde. (A small subset of the 79 moons of Jupiter do not have well-known orbits.)
Most moons, including the Earth's, have prograde orbits. Two of the newly discovered moons, the closest to Jupiter, also have prograde orbits
The other nine moons, grouped into groups of three, have retrograde orbits. These moons were probably part of much larger moons that have fragmented into smaller objects, Sheppard said. Astronomers are currently conducting computer simulations to determine how the old moons have fragmented.
Valetudo is something a little weird. It has a prograde orbit at a distance where the rest of Jupiter's moons have retrograde orbits. Moreover, these orbits intersect. In other words, the scene is set up for possible moon-moon collisions.
Astronomers do not know the composition of the dozen newly identified moons. They could be rock, ice or a mixture. "The only thing we know for now are the orbits and the approximate size," Williams said. "We know nothing, really, more than that."
The kingdom of giant planets – between Jupiter, Saturn, Uranus and Neptune – is largely devoid of small objects. When these planets were formed, their gravity sucked nearby gases, rocks, and other debris. This question has become part of the planets themselves.
But Sheppard suspects that these moons could be remnants, the "last vestiges" of the first objects of the solar system. "Looking at these outer moons," he says, "we can get a glimpse of what were the objects that eventually formed the planets we see today."
(This story was not edited by personal NDTV and is generated automatically from a syndicated feed.)
[ad_2]
Source link
