Saturn runs rings around Jupiter
(2025/03/14)
- Reference: 1741935785
- News link: https://www.theregister.co.uk/2025/03/14/128_more_saturnian_moons/
- Source link:
The International Astronomical Union on Tuesday ratified the recent discovery of 128 previously unknown moons orbiting Saturn, taking the gas giant’s count of known natural satellites to 274.
The ratification mean Saturn goes well ahead of Jupiter, which has a puny population of 95 known moons.
The moons were discovered by a team of astronomers who in 2023 used the Canada France Hawaii Telescope at Mauna Kea in Hawaii to observe Saturn. The
[1]
We know almost nothing about the newly discovered moons because they’re small, distant, and probably not much more than rocks.
[2]
[3]
All have irregular orbits at steep angles compared to Saturn’s equator and are found beyond the planet’s famous rings and well outside the orbits occupied by its major moons.
The scientists who spotted the moons named a 47-strong group “Mundilfari” and apparently speculate they may have been the result of a collision in near-Saturn space that took place as recently as 100 million years ago.
[4]
That’s too early to have killed the dinosaurs by at least 30 million years.
[5]Saturnian moon Mimas: Crunchy on the outside, sub-surface ocean on the inside
[6]Dragonfly delayed – formal confirmation of journey to Saturn's moon slips into 2024
[7]Athena Moon lander officially FOADs – falls over and dies – in crater
[8]Satnav systems built for Earth used by Blue Ghost lander as it approached the Moon
Nature [9]reports that the discoveries were made possible by a combo of more time using the telescope, and techniques that allow captured images to be stitched together. Those techniques were used to find 62 Saturnian moons in 2023 before again being pressed into service for this new set of discoveries.
The International Astronomical Union ratified the moons on Tuesday with three formal documents -one describing [10]thirty-three moons , another detailing [11]thirty-four and the last listing [12]61 satellites .
They’re dense but fascinating documents that list all of the observations during which the satellites were spotted. The document describing 33 moons has 844 lines of observation data!
The documents also include a section detailing each moon’s orbit.
[13]
The moons don’t have names, and the honor of picking them apparently falls to Edward Ashton, a postdoc fellow at the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. Ashton is also lead author of a forthcoming paper describing the newly discovered moons, which will soon appear in Research Notes of the American Astronomical Society. ®
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[5] https://www.theregister.com/2024/02/08/mimas_subsurface_ocean/
[6] https://www.theregister.com/2023/11/29/dragonfly_delayed_formal_confirmation_slips/
[7] https://www.theregister.com/2025/03/07/athena_moon_probe_dies/
[8] https://www.theregister.com/2025/03/06/blue_ghost_lugre_module_acquires/
[9] https://www.nature.com/articles/d41586-025-00781-1
[10] https://minorplanetcenter.net/mpec/K25/K25EF5.html
[11] https://minorplanetcenter.net/mpec/K25/K25EF4.html
[12] https://minorplanetcenter.net/mpec/K25/K25EF3.html
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[14] https://whitepapers.theregister.com/
The ratification mean Saturn goes well ahead of Jupiter, which has a puny population of 95 known moons.
The moons were discovered by a team of astronomers who in 2023 used the Canada France Hawaii Telescope at Mauna Kea in Hawaii to observe Saturn. The
[1]
We know almost nothing about the newly discovered moons because they’re small, distant, and probably not much more than rocks.
[2]
[3]
All have irregular orbits at steep angles compared to Saturn’s equator and are found beyond the planet’s famous rings and well outside the orbits occupied by its major moons.
The scientists who spotted the moons named a 47-strong group “Mundilfari” and apparently speculate they may have been the result of a collision in near-Saturn space that took place as recently as 100 million years ago.
[4]
That’s too early to have killed the dinosaurs by at least 30 million years.
[5]Saturnian moon Mimas: Crunchy on the outside, sub-surface ocean on the inside
[6]Dragonfly delayed – formal confirmation of journey to Saturn's moon slips into 2024
[7]Athena Moon lander officially FOADs – falls over and dies – in crater
[8]Satnav systems built for Earth used by Blue Ghost lander as it approached the Moon
Nature [9]reports that the discoveries were made possible by a combo of more time using the telescope, and techniques that allow captured images to be stitched together. Those techniques were used to find 62 Saturnian moons in 2023 before again being pressed into service for this new set of discoveries.
The International Astronomical Union ratified the moons on Tuesday with three formal documents -one describing [10]thirty-three moons , another detailing [11]thirty-four and the last listing [12]61 satellites .
They’re dense but fascinating documents that list all of the observations during which the satellites were spotted. The document describing 33 moons has 844 lines of observation data!
The documents also include a section detailing each moon’s orbit.
[13]
The moons don’t have names, and the honor of picking them apparently falls to Edward Ashton, a postdoc fellow at the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. Ashton is also lead author of a forthcoming paper describing the newly discovered moons, which will soon appear in Research Notes of the American Astronomical Society. ®
Get our [14]Tech Resources
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[5] https://www.theregister.com/2024/02/08/mimas_subsurface_ocean/
[6] https://www.theregister.com/2023/11/29/dragonfly_delayed_formal_confirmation_slips/
[7] https://www.theregister.com/2025/03/07/athena_moon_probe_dies/
[8] https://www.theregister.com/2025/03/06/blue_ghost_lugre_module_acquires/
[9] https://www.nature.com/articles/d41586-025-00781-1
[10] https://minorplanetcenter.net/mpec/K25/K25EF5.html
[11] https://minorplanetcenter.net/mpec/K25/K25EF4.html
[12] https://minorplanetcenter.net/mpec/K25/K25EF3.html
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[14] https://whitepapers.theregister.com/
Re: What is the lower mass limit for a moon?
Anonymous Coward
I can see the conversations now.
Astronomer 1: I've just discovered a new moon.
Astronomer 2: What's it's mass.
Astronomer 1: XXXX Kg.
Astronomer 2 in an Alec Guinness voice: That's no moon.
Should we Pluto some of them.
Anonymous Coward
We need to draw a line somewhere. When we got too many planets, we invented a cut off point where anything smaller wasn't a planet anymore. If we don't do the same with moons, we'll get to a stage where every ice particle in Saturn's rings gets classified as a moon.
Re: Should we Pluto some of them.
David Harper 1
Well, the next General Assembly of the International Astronomical Union is in August 2027. That should be plenty of time to come up with a definition of "moon" that will satisfy half the planet and annoy the other half.
Re: Should we Pluto some of them.
Kane
"That should be plenty of time to come up with a definition of "moon"..."
Space Station
Re: too early to have killed the dinosaurs by at least 30 million years.
Roj Blake
Not if the rock ended up in an irregular orbit and took 30 million years to reach the Earth.
What is the lower mass limit for a moon?
It seems to me that Saturn has a near infinite number of moons if you would count every clot of dirt circling it. There has to be an agreed lower limit to what is a moon, vs sand/dust for the counts to be meaningful.