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Space Moon

Saturn Solidifies Its Title As Moon King With Discovery of 128 New Moons (www.cbc.ca) 42

Astronomers using the Canada-France-Hawaii Telescope have discovered 128 new moons around Saturn, bringing its total to 274 -- more than all the other planets combined. CBC News reports: Jupiter and Saturn have been locked in a battle for the most moons for years -- with Saturn stealing the crown from Jupiter only two years ago when the same group of researchers found 64 additional moons orbiting it. But scientists say this discovery likely settles the score once and for all. [...] He and the other scientists working on the project made the discovery using the Canada France Hawaii Telescope, a 3.6-meter optical telescope on the summit of the dormant volcano Mauna Kea on the Big Island of Hawaii.

Scientists have been capturing pictures of the moons using the telescope since 2019. The researchers aligned and layered 44 of those images on top of one another in order to enhance the appearance of the moons and determine what they were. These moons are nothing like Earth's very own, however. Sara Mazrouei, a planetary scientist and educational developer at Humber Polytechnic, says that while we tend to think of a spherical shape when we hear the word moon, anything that orbits a planet, or another body in space that is not a sun, is considered a moon. Mazrouei says many of the moons surrounding other planets in our solar system -- including the ones observed here -- are in fact only a few kilometers across in size and oddly shaped, like an asteroid.

Saturn Solidifies Its Title As Moon King With Discovery of 128 New Moons

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  • How is it that Cassiniâ"Huygens didn't capture this detail before. Quite astounding that a probe like Cassini orbited Saturn for 13 (THIRTEEN) years and didn't capture this information.
    • Re:Cassiniâ"Huygens (Score:5, Informative)

      by gtall ( 79522 ) on Saturday March 15, 2025 @07:49AM (#65235423)

      Errrrr....it was not looking for new moons. From the wiki, it's job was

              Determining the three-dimensional structure and dynamic behavior of the rings of Saturn.
              Determining the composition of the satellite surfaces and the geological history of each object.
              Determining the nature and origin of the dark material on Iapetus's leading hemisphere.
              Measuring the three-dimensional structure and dynamic behavior of the magnetosphere.
              Studying the dynamic behavior of Saturn's atmosphere at cloud level.
              Studying the time variability of Titan's clouds and hazes.
              Characterizing Titan's surface on a regional scale.

      It was only going to look at an object for where it knew to look. To find a moon isn't just taking a picture and saying: Yup, thar's one!! You have to observe a fleck of light and it's movement over many pictures. To do that from Earth via Cassini you would have needed it to take many pictures all around the planet over many orbits in what amounts to a 360 degree sphere. And to send a space craft to do what could be done from here is just plain silly.

    • Probably because the mission of Cassini-Huygens was not to find new moons but study aspects of previously known moons like Titan. Even then it found seven new moons during the mission's lifetime.
    • by vyvepe ( 809573 )
      It had only one wide angle camera. You would need about 3400 images to cover the sky when it was already there. You cannot do it in one time. The moons will move by the time you take all the images so you can miss some. Also you need to take a photo of each moon more times to be sure it is in orbit of Saturn. It does not make sense to do it when the probe is already there.
      It might have found some while still far away when one picture can capture more space around Saturn.
    • Further to the other replies, you'd have needed quite high precision in knowing the position and attitude of the spacecraft at the time of taking each photograph (most of which wouldn't contain any new images of previously undetected moons. Which is quite challenging in space. On the ground ... well, we know where the earth is, and how it moves, pretty well. So it's a simple calculation from your clock. On a spacecraft, with multiple thruster actions ... not so easy.

      I also wonder what the limiting magnitud

  • between a moon and an asteroid? I would've thought a moon would be required to be approximately spherical. Similar to a planet.

    • I think the main difference is a moon orbits a planet while an asteroid does not.
    • by Travco ( 1872216 )
      The appropriate question is - where is the cutoff between a moon and a grain of sand It is frankly ridiculous to call some of these things moons. Everything that's orbiting Saturn is a " moon"
    • between a moon and an asteroid? I would've thought a moon would be required to be approximately spherical. Similar to a planet.

      There isn't a consistently universal cut-off for a planet, let alone something that orbits a planet. Turns out the answer is kind of arbitrary, and there are multiple reasonable values.

    • There is no recognized lower threshold in size, though very small orbiting bodies, such as the components of Saturn's rings, are referred to as "moonlets" and not moons. https://en.wikipedia.org/wiki/... [wikipedia.org]

    • Many of these bodies are expected to be "temporary" - the energy needed to remove them from being under Saturnian domination and return them to the Sun being the dominant controller of their movement is quite small. An interaction with Jupiter, or a passing comet may well be enough. They may only have been "moons" for a few tens of millions of years, and only have a few tens of million years left before returning to the general population.

      OTOH, there's a very good reason that Saturn doesn't have the hundre

  • How can a system with 274 moons be "stable"? I mean, it isn't stable in a mathematical sense of view but I guess these moons have been there for millions, if not billions of years, so in a practical sense, the system is stable. How can that be? I would expect the gravity of all these moons change each other's orbit causing collisions, ejecting the moons from Saturn etc? Not every day but maybe every 100 years or so?

    • How can a system with 274 moons be "stable"?

      The same way the Earth is stable with thousands of artificial moons humans placed into orbit. The moons are small and affect the system but being so small the overall gravitational effect is negligible. Remember it has taken this long to find these moons so they must be very small.

    • Nothing is stable. (Probably - there is some debate over the stability of the isolate proton.)

      The Solar system is not stable. It is chaotically variable. That doesn't mean that Neptune and Jupiter are likely to ever swap orbits. But it does mean that, for example, there is about a 1% chance that Jupiter, Earth and Venus can act together to eject Mercury from the system some time before the Sun turns red giant ("after" becomes rather moot). There's about the same chance that such orbital jiggery-pokery will

  • anything that orbits a planet, or another body in space that is not a sun, is considered a moon

    So by that definition all the bits of ice and junk in the rings are individual moons? If not then the Earth says "suck it Saturn". It has over 11k satellites in orbit currently. Maybe Saturn should make itself more hospitable to intellect life so they can throw a bunch of junk into space to get Saturn's moon crown back.

    • If not then the Earth says "suck it Saturn". It has over 11k satellites in orbit currently.

      Other than the fact that these Saturn moons are naturally occurring as opposed the 11k artificial Earth moons humans placed in orbit?

    • Yeah no doubt. According to Wikipedia, there is no recognized lower limit in size, but the rocks within Saturn's rings aren't considered moons, but "moonlets." https://en.wikipedia.org/wiki/... [wikipedia.org]

    • Saturn has on the order of a few quintillion individual satellites. In each of it's 5 rings.
  • I mean, we already have "rock" ...
  • by Vandil X ( 636030 ) on Saturday March 15, 2025 @10:05AM (#65235587)
    We were finding too many "planets" in the Solar System, so humanity changed the definition of "planet" which resulted in demoting Pluto to Dwarf Planet status and a host of other celestial objects.

    I think we should do something similar with "Moons". For example, require the definition to be an oblate spheroid. That would demote almost every captured asteroid to being a "Dwarf Moon".

    Then maybe the Gas Giants won't have a ridiculous number of "Moons" and let the word "Moon" give the correct stereotypical mental image of a spheroid when the term is used.
    • This is an excellent proposal, requiring a spheroid shape to qualify. This is less arbitrary than a dimensional measurement.

      • Sphericity of 0.78893 or more? Or 0.78894?

        (Using the geological definition of sphericity, because I don't think the geometers have one.)

        • Would that be an African swallow, or a European swallow?

          It's a question the scientists can quibble over, either definition is reasonable and could serve as a baseline. The underlying point is that gravity is sufficient to shape the body into a spherical shape.

          • My understanding is that an object has to have a diameter of at least 100 miles for its gravity to be strong enough to pull it into a roughly spherical strength, but of course, I Could Be Wrong. And let's not get into the difference between statute and nautical miles!
  • Saturn made great cars. Can't wait to try out one of their new moons. I bet they are just as reliable.
  • That's No Moon! That's a Space Station!

  • anything that orbits a planet, or another body in space that is not a sun, is considered a moon

    ... Elon vows to take back the title.

  • Did they find Thuktun Flishithy yet?

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