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posted by martyb on Friday October 12 2018, @09:41PM   Printer-friendly
from the jokes-write-themselves dept.

If a Moon Has a Moon, Is Its Moon Called a Moonmoon?

A few years ago, an astronomer's son asked the type of question only kids and genius astrophysicists come up with: Can a moon have a moon? Juna Kollmeier of the Carnegie Institution Observatories couldn't answer her child's query, but she realized that investigating the idea could help answer questions about how moons form and even reveal some of the hidden history of the Solar System, reports Ryan F. Mandelbaum at Gizmodo.

The results, which she co-authored with astronomer Sean Raymond of the University of Bordeaux, were recently published in a short paper titled "Can Moons Have Moons?" on the preprint server arXiv.org, which hosts yet-to-be peer reviewed research. The study, however, has raised an even bigger question that now has the scientific Twitterverse riled up. Just what do you call the moon of a moon?

In their study, Kollmeier and Raymond looked at what would happen to a small submoon orbiting another moon. According to the paper, what they found is that in most cases there's just not enough space for a submoon to orbit another moon. Tidal forces would pull the little moon toward the host planet, ripping the mini moon to pieces.

For a submoon to survive, it needs to be small—about six miles in diameter or less. It also needs to orbit a large moon with enough gravity to hold it in place and must be far enough away from the host planet to complete its own orbit. It turns out that several moons in our own solar system fit the bill and could host submoons, including Titan and Iapetus, which orbit Saturn, and Callisto, which orbits Jupiter. Even our own moon is the right size and distance from Earth to potentially host its very own moon.

Subsatellite.

Also at ScienceAlert, Quartz, and Know Your Meme.


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  • (Score: 0) by Anonymous Coward on Saturday October 13 2018, @12:20PM (6 children)

    by Anonymous Coward on Saturday October 13 2018, @12:20PM (#748276)

    There's an Asteroid coming. Shaped like a skull. They call it 2015 TB145. As in, To Be Determined. And they say it won't hit us. But maybe they're wrong. Who knows? Nobody knows.

    Nobody knows? Only someone who is intentionally ignorant.

    Read and remove your ignorance:

    https://en.wikipedia.org/wiki/2015_TB145 [wikipedia.org]
    http://www.minorplanetcenter.net/db_search/show_object?object_id=2015+TB145 [minorplanetcenter.net]

    Oh, I'm sorry. "Ignorance is bliss" and you like it that way?

  • (Score: 2, Flamebait) by realDonaldTrump on Saturday October 13 2018, @07:11PM (5 children)

    by realDonaldTrump (6614) on Saturday October 13 2018, @07:11PM (#748370) Homepage Journal

    They don't know for sure. Nobody knows for sure what will happen. In life or in Space. And maybe you don't look at your Links. It says there. They call it "uncertainty." Fancy way to say, we don't know for sure!!!

    • (Score: 1, Funny) by Anonymous Coward on Saturday October 13 2018, @09:22PM (4 children)

      by Anonymous Coward on Saturday October 13 2018, @09:22PM (#748398)

      They don't know for sure. Nobody knows for sure what will happen. In life or in Space.

      How tall are you? Six foot 2 inches? Six foot one inch? Six foot 1.5 inches? Six foot 1.75023 inches?

      They don't know for sure.

      And maybe you don't look at your Links. It says there. They call it "uncertainty." Fancy way to say, we don't know for sure!!!

      I look at the links. Not only that, I try to understand them. You may consider doing that.

      Here let me get that [minorplanetcenter.net] for you:

      Uncertainty Parameter U and Orbit Quality Codes Uncertainty Parameter U In order to quantify the uncertainty in a perturbed orbital solution for a minor planet in a concise fashion, the Minor Planet Center has introduced the U parameter. This is an integer in the range 0 to 9, where 0 indicates a very small uncertainty and 9 an extremely large uncertainty. In practice, U is rarely larger than 6.

      The U value is calculated in the following manner. First, calculate:

            RUNOFF = (dT * e + 10 / P * dP) * ko / P * 3600 * 3

      where dT is the uncertainty in the perihelion time (in days)
            e is the eccentricity
            P is the orbital period (in years)
            dP is the uncertainty in the orbital period (in days)
            ko is the Gaussian constant in degrees
               = 180 / pi * 0.01720209895
            3600 converts to seconds of arc
            3 is a empirical factor to make the formal errors more
               closely model reality
      and   RUNOFF is the in-orbit longitude runoff in seconds of
               arc per decade

      RUNOFF is then converted to the "uncertainty parameter" (denoted by 'U') in the range 0 to 9:

            CONS = ln(648000)/9            CONS ~ 1.49
            U = INT(ln(RUNOFF)/CONS)+1  (0 <= U <= 9)

      where ln is the natural logarithm
            INT is a function that returns the largest integer
               smaller than the argument (e.g., INT(3.5) = 3,
               INT(0.99) = 0, INT(-0.45) = -1)

      As a guide, the values of U correspond to the following values of RUNOFF (in seconds of arc per decade):

         U      RUNOFF              U      RUNOFF

         0      < 1.0               5      < 1692
         1      < 4.4               6      < 7488
         2      < 19.6              7      < 33121
         3      < 86.5              8      < 146502
         4      < 382               9      > 146502

      The U value should not be used as a predictor for the uncertainty in the future motion of NEAs.

      What they are saying is that this orbit has a low calculated orbit uncertainty.

      It's as if you launched a nuclear warhead at Tycho Crater [wikipedia.org] on the Moon, or even at a MoonMoon!

      It might get a direct hit.

      Then again, it might miss it by 10 miles. Maybe 20? Unlikely, but maybe 100 miles?

      You are saying people cannot know for certain...

      .... that it might actually hit the White House!!!

      Yes, your statement is about that far off.

      If ever a MoonMoon is found orbiting Luna, I hope they don't let you anywhere near the orbital calculations!

      • (Score: 2) by realDonaldTrump on Monday October 15 2018, @02:06PM (3 children)

        by realDonaldTrump (6614) on Monday October 15 2018, @02:06PM (#749031) Homepage Journal

        Dumb tweet. Because nobody's seen the Skull for YEARS. So nobody knows what's been happening with it. What it's been doing. If you read the stories here -- they're saying, Planet 9. Otherwise known as Planet X. Is pushing things around with its Gravity. The planets, the asteroids -- many things. And possibly it pushed the Skull. NOBODY KNOWS.

        Another thing, they had a story. The Farting Asteroid. Oumuamua. Not sure about the spelling. The media are constantly pouring over my tweets, looking for the misspelling. But, Oumuamua let out a big Fart. And it was like a rocket. Like a blast from a rocket. Maybe the Skull does the same thing -- NOBODY KNOWS.

        The nuclear, we have the best nuclear of anybody. Except possibly for Israel. But it's not PERFECTO. If you look into the history of it, lots of things that didn't go the way they expected. Or the way they wanted. And if I use my Nuclear Button, possibly some of it will land in USA. It could land in Washington, on Trump International Hotel in Washington. Because it's something that our guys built. Regular guys that, at the end of the day, they go home to their families. And maybe a guy had a bad day, maybe he made a mistake. Or maybe he turned into a total nutjob. Or, maybe our nuclear has been hacked so ALL of it lands on us. So it comes back to us. And we won't find out until I launch it. I don't know. And you don't know. NOBODY KNOWS!!

        • (Score: 2) by martyb on Wednesday October 17 2018, @03:43PM (2 children)

          by martyb (76) Subscriber Badge on Wednesday October 17 2018, @03:43PM (#749997) Journal

          Translation: I don't know (and really don't care) how scientists calculate orbits. Of course scientists, who have been doing this all their life, would NEVER think about measurement errors and how that might affect their calculations. Given a clear example of how much I do not understand things explained so that even a five year old could understand... ignorance is bliss and I want to be HAPPY!

          As for the farting orangutan, that would be me. I ate at Taco Bell and those refried beans were really tasty, but... well you KNOW. It was, well, NUCLEAR! I can't say for sure, I might be wrong, but I'm pretty sure it was the beans. We need to get rid of those beans. Put them in orbit around the moon. All of them. Let them clump together under the POWER of GRAVITY! If we did that, then it would be a bean-moonmoon. But it would probably not last long. When that SKULL asteroid sees all those beans.. I tell ya, believe me, they are not going to last. It will gobble them up like CRAZY!

          And those scientists who made mistakes. I tell ya, they never learn anything from their mistakes. They'd never think to make adjustments so they did not repeat past mistakes! And I should KNOW! I sure don't learn anything from my mistakes! No, the only thing that is PERFECTO is ME! People say I never lie. Never say anything unless I think it through and all the possible complications. Smart people! But I'm smarter! Stable GENIUS they call me! Well, some people do. NOBODY KNOWS! Trust me!

          So believe me when I say that Skull asteroid COULD hit a MoonMoon!

          --
          Wit is intellect, dancing.
          • (Score: 4, Interesting) by realDonaldTrump on Thursday October 18 2018, @12:07PM (1 child)

            by realDonaldTrump (6614) on Thursday October 18 2018, @12:07PM (#750403) Homepage Journal

            Dumb tweet. And maybe you're being sarcastic. Or, maybe not. But, dumb either way. You don't read, or don't believe, the stories of SoylentNews. You think they're Fake News. And you're one of the Editors. So interesting. Really says so much!

            9-11, remember the planes? Everybody thought, "oh, these planes are going to L.A. Or San Francisco." Well, they didn't go to L.A. And they didn't go to San Francisco. They were supposed to -- they didn't. They went to NYC -- and Pennsylvania. Because the guys driving them were VERY UNPREDICTABLE. But, I predicted the 9/11 attack on America in my book "The America We Deserve." I happen to think that they had not only a plane, but they had bombs that exploded almost simultaneously.

            By the way, 40 Wall Street actually was the second-tallest building in downtown Manhattan, and it was actually, before the World Trade Center, was the tallest. And then, when they built the World Trade Center, it became known as the second-tallest. And after that horrible day, it became the tallest.

            I said, look at the story about OUMUAMUA. That says, it's a rock. But it's also a rocket. It goes this way, it goes that way. Zigs & Zags. And nobody knows which way it will go. They call it, ASTEROID. And Space Skull is another one. They call it dead comet, it looks dead. Looks like a skull. But possibly it's not dead. And suddenly, Zig. Zag. And it goes somewhere UNPREDICTABLE. Like me!!!

            • (Score: 2) by martyb on Thursday October 18 2018, @07:59PM

              by martyb (76) Subscriber Badge on Thursday October 18 2018, @07:59PM (#750623) Journal

              Yes, my comment was intended to be funny, but I accidentally left off the "=)" smiley. My bad!

              And it goes somewhere UNPREDICTABLE. Like me!!!

              And... you got a genuine LOL out of me with that one. That got you a "+1 Funny" from me!

              --
              Wit is intellect, dancing.