Saturn now has more moons than all the other planets combined!

For decades, Jupiter and SatSat This, in turn, leads the race for the largest number of known satellites. After announcements ofWinterWinter The latter raised the orange giant’s counter to 95 known moons, now a planet famous for its majestic rings, which has seen its number of identified companions increase. In fact, 62 new irregular satellites of Saturn were discovered, doubling their number from 59 to 121. Add to this the 24 known regular satellites, and this the doorthe door Saturn has a total of 145 known moons, or 50 more than Jupiter! Saturn becomes the first planet to know more than 100 companions on this occasion.

Dozens of small satellites in Saturn’s outer suburbs

This remarkable result is the result of the work of an international team led by Edward Ashton, currently a postdoctoral researcher at the Astronomical Institute andAstrophysicsAstrophysics From Academia Sinica, Taiwan. The group also includes Brett Gladman, a professor in the department BodyBody and Astronomy from Mike Alexanderson, University of British Columbia (Canada). Harvard Smithsonian Center for Astrophysics (United States), Jean-Marc Petit, from the Besancon Laboratory (France), and Mathieu Beaudoin, from the University of British Columbia.

Over the past two decades, Saturn’s surroundings have been repeatedly scanned for small moons with ever-increasing sensitivity. In Their latest studyEdward Ashton and his collaborators “Moving and Stacking” (” Shift and stack in English) in order to detect less bright and smaller satellites. The technique has previously been used to search for moons of Neptune and Uranus, but never before for Saturn. Move a set of contiguous images to SpeedSpeed The movement of the moon across the sky amplifies the signal from this companion when combining the data, allowing the “stacked” image to show satellites that are too faint to be seen in individual images. The team used data obtained by the Canada-France-Hawaii Telescope (CFHTCFHT) between 2019 and 2021. Obtained by moving and stacking multiple consecutive images PeriodsPeriods Three hours later, the crew managed to find out moonsmoons It is just 2.5 kilometers in diameter.

Finding an object near Saturn in the sky does not guarantee that it is a satellite: it just might be AsteroidAsteroid It goes through the planet, though it’s unlikely. To certify that an object actually exists Around the circular pathAround the circular path Around the planet, it should be followed for many years. After painstakingly matching objects detected on different nights over two years, the team was able to track 63 objects that were confirmed to be new satellites. There was one of these moons designated S/2019 S 1 Announced in 2021 ; The rest started announcing in the last two weeks and should be completed this week. For some objects, observations dating back many years have been found, at which time they did not allow us to determine the orbit around Saturn.

” Tracking these moons reminds me of the dot to dot game I used to play as a kid, as we have to match the different appearances of these moons with possible orbits in our data, but with 100 different games on the same page and without. Knowing which point belongs to which game “, explains Edward Ashton.

Clusters of satellites resulting from collisions

All of these new companions are irregular satellites that are believed to have been captured by the planet long ago. Irregular satellites are characterized by wide, elliptical and inclined orbits unlike regular satellites.

Irregular satellites tend to form groups whose members have an inclination orbitorbit similar. In the case of Saturn, three groups are defined as follows: Gallic group (about 36° declinationEclipseEclipse), the Inuit group (around 48°) and the Nordic group (retrograde orbits, typically with an inclination between 140 and 180°). These three groups are named after the Puranas from which the names given to their respective members are taken. Of the 63 satellites discovered around Saturn since 2019, eight belong to the Inuit group, two to the Gallic group, and fifty-three to the Nordic group. This last group is the most populous group, uniting the 99 satellites known so far. The Inuit group now has fifteen identified members, while the Gallic group has seven. All these objects are located between 11 and 25 million kilometers from Saturn.

These groups are thought to be the result of collisions: the current satellites of a given group are the products of one or more collisions that affected the satellites initially captured by the planet. A better understanding of the distribution of orbits gives us clues about the collisional history of Saturn’s irregular moon system. From their past study of these objects, the team suggested that the large number of small moons in retrograde orbits formed from the relatively recent extinction (in astronomical terms, i.e. within the last 100 million’ years) of an intermediate-sized irregular satellite. A number of pieces listed in the Nordic group.

According to Jean-Marc Petit, “ The study of irregular moons tells us about the final stages of the formation of the solar system. But the benefits of observing closer planets (brighter moons) are offset by a larger area to observe, and shorter views before the Moon moves into the picture, so no planet is easier to study than another. “.