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Thread: Astronomy

  1. #1141
    On the road, but not! Danik 2016's Avatar
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    Additional link about the end of the Cassini mission:

    https://saturn.jpl.nasa.gov

    I shouldn´t wonder if they make a science fiction movie about the mission.
    One thing I am learning from these researches is that the composition and the atmosphere of the planets varies a lot from one to another.
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  2. #1142
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    Yes, the variety among "hot jupiters" is staggering. See this post: https://www.universetoday.com/137199...et-eats-light/

  3. #1143
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    https://www.universetoday.com/137205...-solar-system/ presents a much more coherent theory of the way solar systems develop, based on the fact that a "planet 9" or "Planet X" exists. The first designation assumes that is a dwarf planet, an idea that has already been rejected by the new definition which re-classifies Pluto as a planet: https://en.wikipedia.org/wiki/Planet_Nine. So "planet X" is probably less controversial.

  4. #1144
    On the road, but not! Danik 2016's Avatar
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    They are messing around a lot with Pluto these days. I consider him a planet, because in astrology is a very influential one.


    Here some more pictures taken by the Cassini expedition:

    Farewell, Cassini: Gorgeous Final Photos Are a Fitting Send-Off for Saturn Probe

    https://www.space.com/38174-cassini-...ll-photos.html
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  5. #1145
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    http://earthsky.org/space/pitch-blac...lanet-wasp-12b This is a similar post to the one above 1142, but more detail.

  6. #1146
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    Amazing image of this dark planet!
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  7. #1147
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    Yes, it is so hot that it absorbs the light, rather than reflects it! Not that I understand why this should be...

  8. #1148
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    Quote Originally Posted by Danik 2016 View Post
    They are messing around a lot with Pluto these days. I consider him a planet, because in astrology is a very influential one.
    Astronomers couldn't care less how important astronomical objects are to astrologists.

    So *within astronomy*, is Pluto still considered a planet? A quick Google search seems to indicate there are still two camps. In 2006, when it was demoted by some astronomers, the main argument was that a larger Kuiper belt object (Eris) existed. But they weren't *certain* it was larger! Now it appears that Pluto is actually larger, and is the largest object in the Kuiper belt. Another determining factor for a planet, according to some, was that it should have cleared its orbit of other objects. As there were all these Kuiper objects, Pluto hadn't done this, ergo it wasn't a planet. But, someone pointed out, with all these asteroids & comets coming near the Earth, obviously the Earth hadn't cleared its orbit, so it wasn't a planet! To me, it would seem reasonable to keep Pluto as a planet, and then define a planet as anything at least as large as Pluto. (They still reckon Eris is more massive, so *size* should be the determining factor . But the whole problem here seems to be in finding a set of really good reasons for calling something a planet or not...)

  9. #1149
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    I am not at all sure what the new definition of a planet is. What has been decided exactly?

  10. #1150
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    There is clearly a lot more water in the solar system that was previously thought. I thought this piece on Mars is just another example, at least of how Mars used to be in the distant past: http://earthsky.org/space/more-evide...-water-on-mars

  11. #1151
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    I agree with you. I found a link to the NASA definition of planet(below).
    In Astrology Pluto, the regent of Scorpio, is a planet that relates to the great changes (in people, places or situations) that irrupt from the interior. For example he is related to the earthquakes,
    Last edited by Danik 2016; 09-21-2017 at 10:32 PM.
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  12. #1152
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    These seems to be be the current situation:
    "The International Astronomical Union (IAU), a worldwide organization of astronomers, took on the challenge of classifying the newly found KBO (later named Eris). In 2006, the IAU passed a resolution that defined planet and established a new category, dwarf planet. Eris, Ceres, Pluto, and two more recently discovered KBOs named Haumea and Makemake, are the dwarf planets recognized by the IAU (as of July 2013). Pluto, Eris, Haumea, and Makemake are also classified as KBOs, and Ceres retains its asteroid label. There may be another 100 dwarf planets in the solar system and hundreds more in and just outside the Kuiper Belt.

    Astronomers and planetary scientists did not unanimously agree with these definitions. To some it appeared that the classification scheme was designed to limit the number of planets; to others it was incomplete and the terms unclear. Some astronomers argued that location (context) is important, especially in understanding the formation and evolution of the solar system."
    https://solarsystem.nasa.gov/planets/whatisaplanet
    "I seemed to have sensed also from an early age that some of my experiences as a reader would change me more as a person than would many an event in the world where I sat and read. "
    Gerald Murnane, Tamarisk Row

  13. #1153
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    I thought the IAU had changed its definition of dwarf planet by dropping the criterion of having "cleared their orbit (?)" (whatever that may mean), but it seems they have not, just widened the definition to include more "dwarf planets". Your last paragraph (above) accurately reflects the confusion around this whole question.

  14. #1154
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    The subject is still unresolved.

    See the long discussion here: https://en.wikipedia.org/wiki/IAU_definition_of_planet.

    And the discussion around "clearing the neighbourhood": https://en.wikipedia.org/wiki/Cleari..._neighbourhood.

    For me this is the key issue. Has Earth "cleared its neighbourhood"? Not according to some, and I have to say I tend to agree.

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