The discovery of 62 previously unknown moons put the ringed planet back in the lead with a total of 145 officially recognized moons. That means Big Jupe (Jupiter), with its 92 known moons, will have to make some tough moves if it wants to reclaim the crown. But more importantly, it demonstrates the technique’s effectiveness in detecting small moons around giant planets.

By scrolling and superimposing images of the moons taken over several years, a team led by astronomer Edward Ashton of the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan was able to locate the 2.5-kilometer-wide moons of Saturn.

And these newly discovered tiny moons are allowing astronomers to piece together Saturn’s past.

In fact, small moons orbiting Jupiter and Saturn are quite difficult to detect. These two planets are the largest planets in the solar system and they are very bright in the sky, especially from our view of Earth where they are always illuminated by the sun.

This means they largely outshine everything around them, making small dim objects particularly difficult to detect. It is interesting that the criteria for identifying a satellite or a natural satellite are quite broad. There are no requirements for shape, mass, diameter or composition; it is sufficient for the object in question to have a stable orbit around another larger non-star object. That’s why planets, dwarf planets, and even asteroids can have their own moons.

But it’s not enough to detect an object near a planet and claim you’ve found a new moon. The object needs to be tracked – ideally in multiple orbits – so that its path can be analyzed and whether it is stable or not. Therefore, although panning and overlapping can reveal faint objects, many such observations are necessary to confirm the Moon’s state.

Here’s how it works. The successive set of images “slips” at the same speed as the moon moves across the sky. These images are then stacked; this is a technique that amplifies signals that are too weak to be seen in a single image and makes them brighter for scientists to see.

This slide-and-pick technique was used to find moons orbiting Uranus and Neptune; In 2019, Ashton and colleagues used the Canada-France-Hawaii Telescope (CFHT) to scan the sky around Saturn and identified previously unknown objects in space around Saturn.

From then until 2021, they made periodic observations for three hours, shifting and stacking the resulting images to check whether the detected objects were satellites. They chose 63 new moons, one of which was announced in 2021. They have now diligently approved the other 62.

“Tracking these satellites makes me think of the kid’s game Dot-to-Dot because we need to associate different types of these satellites in our data with a valid orbit, but there are about 100 different games on a page and you don’t do that. I don’t know which dot belongs to which puzzle,” says Ashton. .

All newly discovered moons belong to Saturn’s three groups of moons classified as “irregular”. Grouped into groups known as the Inuit, Gallic, and Scandinavian moons, these moons orbit the planet in large elliptical orbits inclined to the “normal” moons of Saturn.

Most new moons belong to the Nordic group, which is the most densely populated and has the greatest orbital distance of the three. It also rotates in the opposite direction of Saturn. Astronomers have interpreted these groups as evidence of moon-to-moon collisions that occurred at some point in Saturn’s recent past, leaving small swarms of moons behind.

According to the analysis, the Scandinavian group may be what remains after the destruction of a medium-sized irregular moon. The recently discovered satellites are further proof of this, the researchers say.

“As we reach the capabilities of modern telescopes, we’re finding more and more evidence that a medium-sized moon orbiting Saturn broke up about 100 million years ago,” says astronomer Brett Gladman of the University of British Columbia in Canada.