Saturn now has a total of 274 moons<\/p>\n
NASA\/JPL\/Space Science Institute<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
A further 128 moons have been discovered orbiting Saturn, bringing the planet\u2019s total to 274 \u2013 more than there are around all the other planets in our solar system combined. But as advances in telescope technology allow us to spot progressively smaller planetary objects, astronomers face a problem: how tiny can a moon be before it is just a rock?<\/p>\n
Edward Ashton at Academia Sinica in Taipei, Taiwan, and his colleagues found the new moons with the Canada-France-Hawaii Telescope, revealing dozens that have previously evaded astronomers. They took hours of images of Saturn, adjusted them for the planet\u2019s movement through the sky and stacked them on top of each other to reveal objects that would otherwise be too dim to see.<\/p>\n
All the new moons are between 2 and 4 kilometres in diameter and are likely to have been formed hundreds of millions or even billions of years ago in collisions between larger moons, says Ashton.<\/p>\n
\u201cThese are small little rocks floating in space, so some people might not find it quite an achievement,\u201d says Ashton. \u201cBut I think it\u2019s important to have a catalogue of all the objects in the solar system.\u201d<\/p>\n The dot at the centre of this image is one of the new \u201cfuzzy blob\u201d moons of Saturn<\/p>\n Edward Ashton et al. (2025)<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n <\/p>\n Despite the wealth of data gathered by his team, these latest moons still only appear as \u201cfuzzy blobs\u201d, says Ashton. There are more powerful telescopes that could potentially resolve the moons in more detail,\u00a0<\/strong>although many have smaller fields of view, which would mean taking many more images, he says.<\/p>\n The newly discovered moons have been recognised by the International Astronomical Union (IAU), and Ashton and his team\u00a0<\/strong>will now get the right to name them. Ashton, who is Canadian, says he has approached a representative from Canada\u2019s Indigenous peoples for suggestions, but is also mulling the idea of some kind of public naming contest.<\/p>\n Could there be more moons out there? Scientists have spent decades scanning the area around Saturn with increasingly powerful telescopes, which has paid off in recent years. In 2019, 20 new moons were found, and Ashton and his colleagues had already discovered 62 in 2023, separate from the 128 they most recently found. Ultimately, it is likely that further discoveries will require advances in telescope technology, says Ashton, who believes there are easily thousands of moons in orbit around Saturn, even discounting the smaller, rocky debris found in the planet\u2019s rings.<\/p>\n Mike Alexandersen at the Minor Planet Center, which logs planetary bodies for the IAU, says there are likely to be many more moons yet to be found in our solar system as improvements to telescopes allow them to see smaller objects. He says decisions will have to be made about what does and doesn\u2019t count as a moon.<\/p>\n \u201cI do know that the IAU decided that, due to the number of moons that are likely to exist, they\u2019re not going to prioritise naming anything that\u2019s smaller than 1 kilometre. But that\u2019s not the same as them not recognising it as a moon,\u201d says Alexandersen. \u201cThey\u2019ll probably only name it if a spacecraft goes to visit it.\u201d<\/p>\n He suggested that the cutoff between what is a moon and what is just a rock particle that makes up part of a planetary ring is probably going to be somewhere between 1 kilometre and 1 metre in diameter. \u201cIn the end, it probably won\u2019t be my decision, it\u2019ll be the IAU, which will make up some cutoff which will be more or less controversial \u2013 just like the cut for what\u2019s a planet or not. And it\u2019s most likely going to be relatively arbitrary,\u201d says Alexandersen.<\/p>\n Elizabeth Day at Imperial College London says that, one day, there may even be commercial reasons for having accurate maps of the solar system. \u201cWe might want to extract resources from asteroids and moons in the solar system, so having a great understanding of what is where is important for that,\u201d says Day.<\/span><\/p>\n Discover the giant legacy of the Renaissance period astronomers, Johannes Kepler and Tycho Brahe, in Prague, the city of a hundred spires, where astronomy, maths, music and art connect.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n![\"\"](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2025\/03\/10133559\/SEI_243311417.jpg\")
<\/div>![\"New](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2022\/05\/25152155\/klementium-baroque-hall-source-klementium.jpg\")
\n <\/picture>\nRenaissance astronomy in Kepler’s Prague: Czech Republic<\/h3>\n