In the red corner, Jupiter, the largest planet orbiting our Sun, shaped our Solar System with its gravitational pull.
In the blue corner, Saturn, a magnificent ringed world with dazzling hexagonal storms at its poles.
These two giant worlds are late in the race for satellite-based supremacy. But the battle of which planet has more moons in orbit has now turned in favor of Saturn.
This month, the International Astronomical Union is set to approve 62 additions Moons of Saturn Based on the collection of objects discovered by astronomers. The smaller objects would give Saturn 145 moons — eclipsing Jupiter’s total of 95.
They both have many moons, but Saturn “appears to be significantly larger,” said Scott Shepherd, an astronomer at the Carnegie Institution for Science in Washington.
Saturn’s newly discovered moons are nothing like the brightest object in Earth’s night sky. They are irregularly shaped like potatoes, and not more than a mile or two across. Compared to larger moons like Titan, which mostly orbit within a million miles of Saturn, they orbit farther from the planet, between six million and 18 million miles. Yet these little irregular moons are fascinating in their own right. They are often clustered together and may be the remnants of large moons that disintegrated while orbiting Saturn.
“These moons are very important for understanding some of the big questions about the Solar System,” said Bonnie Purati of NASA’s Jet Propulsion Laboratory in California and associate project scientist on the upcoming Europa Clipper mission to Jupiter. “They have fingerprints of events in the early solar system.”
The number of waxing moons highlights potential debates about what constitutes a moon.
“The simplest definition of a moon is that it is an object that orbits a planet,” said Dr Shepherd. The size of an item doesn’t matter for now.
The new moons were discovered by two teams, one led by Dr. Shepherd and the other recently discovered by Edward Ashton of the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. Dr Shepherd’s team used the Subaru Telescope in Hawaii to hunt for more moons around Saturn in the mid-2000s.
In March, Dr. Shepard claimed responsibility for the discovery 12 new moons of Jupiter, temporarily taking over Saturn in the battle to be the biggest hoarder of the moons. That record was short-lived, it seems.
Dr. Ashton Group, 2019 to 2021, Canada France Hawaii Telescope, Subaru Telescope Neighbor on Mauna Kea, Search for More of Saturn’s Moons Dr. Used to verify some of Sheppard’s findings. For a moon to be recognized, it must be spotted multiple times, “observations to make sure it’s a satellite, not just an asteroid that happens to be near the planet,” said Mike Alexanderson, who is in charge of official confirmation of moons at the International Space Station. Astronomical Union.
Most of Saturn’s irregular moons orbit the planet, which astronomers call the Inuit, Norse and Gaelic groups. The material in each group may be the remnants of large moons up to 150 miles across that once orbited Saturn but were destroyed by impacts from asteroids or comets or by collisions between the two moons. “This shows that there is a large collisional history around these planets,” Dr Shepherd said.
Those original moons were probably captured by Saturn “very early in the solar system,” perhaps in the first few hundred million years of its formation, about 4.5 billion years ago, Dr. Ashton said. Not all orbits belong to these groups, however, and a few rogue moons orbit retrograde—that is, opposite to the orbits of other moons.
“We don’t know what’s going on in those retrograde moons,” Dr Shepherd said. Dr. Ashton suspects they may be remnants of a recent conflict.
New moons are difficult to learn more about because of their small size and distant orbits. They appear to be a special class of material distinct from asteroids and comets in the outer Solar System that formed in the inner Solar System. But not much is known.
“These substances can be unique,” Dr. Shepherd said. “They may be the last remnants of what formed in the giant planet region, a very icy object.”
NASA’s Cassini spacecraft was able to observe About two dozen moons Until the destruction of Saturn in 2017. Although not close enough to study in detail, the data allowed scientists to determine the “rotational period” of some moons, the spin axis and “even the shape,” Tilman Denk said. From the German Space Center in Berlin, he led the observations. Cassini also found a large amount of ice on the surface One of the great irregular moonsPhoebe.
Closer observations of Saturn’s small moons could give scientists a window into a turbulent time in the early solar system. During that period, collisions were more common and the planets jockeyed for position, and Jupiter is thought to have moved closer to the Sun to its current orbit. “It gives you more information about the formation of the solar system,” Dr. Denk said.
Yet the erratic moons we’ve seen so far may be just the beginning. “We estimate there could be thousands around Saturn and Jupiter,” Dr Ashton said. There may be many irregular moons, such as Uranus and Neptune, but their vast distances from the Sun make them difficult to find.
Saturn, though smaller than Jupiter, appears to have many irregular moons. It can be up to two miles across, three times the size of Jupiter. The cause is unclear, Dr. Ashton said.
Jupiter’s original moons were likely larger and less prone to erosion. Or maybe Saturn has captured more objects in its orbit than Jupiter. Or Saturn’s moons could have been in orbits that were more likely to collide with each other, creating smaller, irregular moons.
Whatever the reason, the result is clear. Jupiter is on the ropes and is unlikely to regain the title of the planet with the most moons. As astronomers’ abilities to detect smaller and smaller satellites improve, “Saturn will win by miles,” Dr. Alexanderson said. “I don’t think it’s a competition.”