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posted by takyon on Thursday October 12, @10:21AM   Printer-friendly
from the Rings-Past-Uranus dept.

It's not just Saturn and gas giants such as Uranus which have rings in our solar system – as a tiny dwarf planet has just been spotted with its very own.

It's the first dwarf planet beyond Neptune to be spotted with its own ring – and could prove that such rings are not uncommon in the outer solar system.

takyon: Haumea has two known moons as well as this newly discovered ring:

A stellar occultation observed on 21 January 2017 indicated the possibility of a ring system around Haumea. As published in Nature on 11 October 2017, this occultation was confirmed to be a ring, representing the first such ring discovered for a TNO. The ring has a radius of about 2,287 km, a width of ~70 km and an opacity of 0.5. The ring plane coincides with Haumea's equator and the orbit of its larger, outer moon Hi'iaka. The ring is close to the 3:1 resonance with Haumea's rotation.

Haumea is known for its extremely elongated shape, a consequence of its rapid rotation.

The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation (DOI: 10.1038/nature24051) (DX)


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A Return to Pluto and Other Solar System Targets 10 comments

Astronomers are still hoping for another mission to Pluto, or perhaps another Kuiper belt object:

A grassroots movement seeks to build momentum for a second NASA mission to the outer solar system, a generation after a similar effort helped give rise to the first one. That first mission, of course, was New Horizons, which in July 2015 performed the first-ever flyby of Pluto and is currently cruising toward a January 2019 close encounter with a small object known as 2014 MU69.

[...] Nearly three dozen scientists have drafted letters in support of a potential return mission to Pluto or to another destination in the Kuiper Belt, the ring of icy bodies beyond Neptune's orbit, Singer told Space.com. These letters have been sent to NASA planetary science chief Jim Green, as well as to the chairs of several committees that advise the agency, she added. "We need the community to realize that people are interested," Singer said. "We need the community to realize that there are important, unmet goals. And we need the community to realize that this should have a spot somewhere in the Decadal Survey." That would be the Planetary Science Decadal Survey, a report published by the National Academy of Sciences that lays out the nation's top exploration priorities for the coming decade.

New Horizons 2 was already cancelled due to a shortage of plutonium-238, which still reportedly persists. One proposed target was 47171 Lempo, a trinary system. The trans-Neptunian dwarf planets Eris, Haumea, Sedna, Orcus, Salacia, Makemake, and 2007 OR10 (the largest known body in the solar system without a name - with an estimated 1,535 km diameter) have all been discovered since 2002. Several of these TNOs have moons and Haumea was recently found to have a ring system.

Now that Cassini is dead, most new NASA missions are focused on Mars and Jupiter, leaving the solar system's "ice giants" relatively unstudied:

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  • (Score: 2) by bzipitidoo on Thursday October 12, @02:43PM (7 children)

    by bzipitidoo (4388) on Thursday October 12, @02:43PM (#581148) Journal

    Cool, dwarf planets can have moons and rings. If it quacks like a duck... well, you know. This quacks like certain large planets in a solar system.

    Maybe a simple semantics trick? Call them all planets, and add a modifier to the big ones, instead of the little ones. Call the big ones "major planets", "super planets", "power planets", or ... well, something.

    • (Score: 3, Funny) by bob_super on Thursday October 12, @05:11PM (5 children)

      by bob_super (1357) on Thursday October 12, @05:11PM (#581221)

      Knowing astronomers, it would be "Large Planet, Very Large Planet, Extremely Large planet, 30m planet and Overwhelmingly Large Planet [cancelled]"

      • (Score: 0) by Anonymous Coward on Thursday October 12, @05:55PM (4 children)

        by Anonymous Coward on Thursday October 12, @05:55PM (#581246)

        How about they just make it simple, anything that forms a spherical shape due to it's own gravity is a planet. Yes you can exempt stars and derivatives there-of, but you really don't have to. I know I'm asking for too much, these are the same type of people that call the same thing three different things depending on where it actually is.

        • (Score: 0) by Anonymous Coward on Thursday October 12, @10:23PM (3 children)

          by Anonymous Coward on Thursday October 12, @10:23PM (#581390)

          I like the current definition that says it has to dominate its orbit and clear out any stuff there.

          The International Astronomical Union also specifies that a planet must orbit around only one object (a star).

          .
          I also like the word planetoid for lesser objects.

          .
          it's own gravity

          it's == it is; it has
          its == belongs to it
          A pronoun never needs an apostrophe to make it plural. (its, ours, yours, hers, theirs)

          -- OriginalOwner_ [soylentnews.org]

          • (Score: 2) by bob_super on Friday October 13, @12:47AM (1 child)

            by bob_super (1357) on Friday October 13, @12:47AM (#581463)

            > I like the current definition that says it has to dominate its orbit and clear out any stuff there.

            Almost all major planets have moons and trojans. I don't know why they have a definition that needs extra clarification.

            Is it over 90% round, bigger than a breadbox, orbiting a star with an excentricity below 90%, and any objects orbiting it don't bring that system's center of mass outside of the body? It's a planet.
            KISS.

            • (Score: 0) by Anonymous Coward on Friday October 13, @06:39AM

              by Anonymous Coward on Friday October 13, @06:39AM (#581604)

              Heh. Yeah.

              -- OriginalOwner_ [soylentnews.org]

          • (Score: 1) by toddestan on Saturday October 14, @05:03PM

            by toddestan (4982) on Saturday October 14, @05:03PM (#582334)

            The International Astronomical Union also specifies that a planet must orbit around only one object (a star).

            Actually, not "a star", but "the Sun". So yes, by definition there are only eight planets in the entire universe.

    • (Score: 2) by takyon on Thursday October 12, @06:39PM

      by takyon (881) <{takyon} {at} {soylentnews.org}> on Thursday October 12, @06:39PM (#581270) Journal

      "Centaurs [wikipedia.org]" can also have rings

      --
      [SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
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