Twenty new moons of Saturn found
Each of these new moons of Saturn are about five kilometres (three miles) in diameter.
A team led by Carnegie's Scott S. Sheppard have discovered 20 new moons orbiting Saturn, bringing Saturn’s total moon count to 82, therefore surpassing Jupiter's moon count of 79. The moons have been discovered using the Subaru telescope atop Mauna Kea in Hawaii.
About the new Moons:
Each of these new moons of Saturn are about five kilometres (three miles) in diameter. Seventeen of them have retrograde motion, which means they orbit Saturn in the backward direction, opposite to the rotation and axis of Saturn.
The other three are prograde. Two of these prograde moons that are close to Saturn take about two years to travel around the sun. Taking an example of the earth, our moon takes around 27 days to rotate around the earth.
The rest of the moons, including the one with prograde rotation, takes around three years to go around Saturn.
How are they categorised?
The moons orbiting around Saturn are grouped differently (into three) depending on the inclination of the angles at which they are orbiting around the planet. Two of the newly discovered planets that are on the outer side of the planet have an inclination of 46 degrees. They are called the Inuit group, named after Inuit mythology.
“Studying the orbits of these moons can reveal their origins, as well as information about the conditions surrounding Saturn at the time of its formation,” Sheppard explained.
How they were formed?
These moons are expected to have broken apart a long time ago from a larger moon. The newly discovered moons with retrograde motion have similar inclination to the previously existing retrograde Saturnian moons. This indicates that they might be a fragment of a larger parent moon that broke apart into pieces. These retrograde moons are grouped as the Norse group, named for Norse mythology.
“This kind of grouping of outer moons is also seen around Jupiter, indicating violent collisions occurred between moons in the Saturnian system or with outside objects such as passing asteroids or comets,” explained Sheppard.
The odd one out:
One of the discovered moons is the farthest known moon around Saturn. It orbits much farther than any prograde moons. This indicates that it might have been pulled outwards or might not have been the part of the inner prograde moons.
Other moons have an inclination of 36 degrees; these are similar to other groups of inner prograde moons called the Gallic group.
According to scientists, the planets could have spiralled into the planet if they broke apart from a larger moon with a significant amount of gas or dust. This is because of the strong interaction between the smaller moons and the gas and dust surrounding them.
“In the Solar System’s youth, the Sun was surrounded by a rotating disk of gas and dust from which the planets were born. It is believed that a similar gas-and-dust disk surrounded Saturn during its formation,” Sheppard said.
“The fact that these newly discovered moons were able to continue orbiting Saturn after their parent moons broke apart indicates that these collisions occurred after the planet-formation process was mostly complete and the disks were no longer a factor,” he added.