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  • Originally posted by Evan View Post
    Well, it looks like we may soon be considered as living on a binary planet system.

    A top researcher at NASA wants the description changed and there is a lot of agreement. We could end up with as many as 25 planets.
    So what is their definition of a "moon".... if they even admit the existence of "moons", which it appears they almost do not? Presumably something orbiting a "planet", but which does not otherwise satisfy the definition of "planet".
    CNC machines only go through the motions.

    Ideas expressed may be mine, or from anyone else in the universe.
    Not responsible for clerical errors. Or those made by lay people either.
    Number formats and units may be chosen at random depending on what day it is.
    I reserve the right to use a number system with any integer base without prior notice.
    Generalizations are understood to be "often" true, but not true in every case.

    Comment


    • It is all in the article. The definition of planet is any body that has enough silicaceous or denser mass and is able to assume a generally globular shape. It may or may not include water worlds depending on if they are frozen or not. But anything that is rock and is about "round" is a planet. If you read the article you will see why the current definition is totally inconsistent with reality.

      edit: The barycentre does not enter into it at all. It may orbit anything and if it orbits the sun that is good enough. In our case the Moon barycentre will leave the Earth surface and that strengthens the argument although it really doesn't matter.

      I should mention I didn't go looking for this but it popped up in my Google news since I have it selected to tell me about science in general.
      Last edited by Evan; 02-20-2017, 05:35 PM.
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      • Originally posted by J Tiers View Post
        So what is their definition of a "moon".... if they even admit the existence of "moons", which it appears they almost do not? Presumably something orbiting a "planet", but which does not otherwise satisfy the definition of "planet".
        By this new definition, "moons" would no longer exist.

        Who says scientists can't be driven by non-scientific motives? This proposal seems to be more about continued funding than actual science.

        "In the mind of the public, the word “planet” carries a significance lacking in other words used to describe planetary bodies. In the decade following the supposed “demotion” of Pluto by the International Astronomical Union (IAU), many members of the public, in our experience, assume that alleged “non-planets” cease to be interesting enough to warrant scientific exploration, though the IAU did not intend this consequence. To wit: a common question we receive is, “Why did you send New Horizons to Pluto if it’s not a planet anymore?” To mitigate this unfortunate perception, we propose a new definition of planet...

        In our numerous talks with the public, we find they resonate happily with the geophysical definition we offer, especially as it is a definition reflecting a body’s intrinsic physical properties, not its location, and is a definition that leverages their intuition. This definition highlights to the general public and policymakers the many fascinating worlds in our Solar System that remain unexplored and are worthy of our exploration, along with the necessary budgets."

        Comment


        • Well at one time by the definition of the terracentric model of the solar system the SUN was a planet that orbited around the earth. It's only been a few hundred years since Copernicus and his buddies that we've had a solarcentric model based on the actual situation.

          But moons are planets? GIVE ME A BREAK! ! ! ! I suppose I can accept the idea that these are binary or otherwise complex planetary systems. But a moon is a moon is a moon. And what about Mars where the two moons are almost certainly just larger asteroids that Mars managed to capture when they tried to run away? I know the "definition" allows for that since they are mostly not round.

          I think someone at NASA had too much time on their hands or is desperate for new ways of gaining funding...... I'm sorry but that's just a lot of drivel.
          Chilliwack BC, Canada

          Comment


          • Originally posted by BCRider View Post
            Well at one time by the definition of the terracentric model of the solar system the SUN was a planet that orbited around the earth. It's only been a few hundred years since Copernicus and his buddies that we've had a solarcentric model based on the actual situation.

            But moons are planets? GIVE ME A BREAK! ! ! ! I suppose I can accept the idea that these are binary or otherwise complex planetary systems. But a moon is a moon is a moon. And what about Mars where the two moons are almost certainly just larger asteroids that Mars managed to capture when they tried to run away? I know the "definition" allows for that since they are mostly not round.

            I think someone at NASA had too much time on their hands or is desperate for new ways of gaining funding...... I'm sorry but that's just a lot of drivel.
            It's a proposal by a handful of planetary scientists, and it's clearly for the benefit of their field of study. I doubt it will go anywhere.

            Comment


            • What they do not mention in that article is the problems they are having with the thousands of planets they have detected around other stars. They want a definition that can cover those as well and that totally changes the definition now in use. The major argument against the present definition is that a planet has cleared its orbital path of space junk. Even the Earth couldn't do that if it was out at the Pluto range. So what would that make the Earth, other than cold?

              The current definition is very inconsistent with reality. We need a better one and it isn't just about funding or the general public. Regardless, there are already many that consider Earth/Moon to be a binary planet.

              https://www.umich.edu/~lowbrows/refl...warshow.7.html

              http://www.esa.int/Our_Activities/Sp..._double_planet

              From the European Space Agency:




              http://curious.astro.cornell.edu/abo...anets-beginner
              Last edited by Evan; 02-20-2017, 07:27 PM.
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              • Originally posted by Evan View Post
                What they do not mention in that article is the problems they are having with the thousands of planets they have detected around other stars. They want a definition that can cover those as well and that totally changes the definition now in use.
                Here's the part of the definition in question:

                "A celestial body that (a) is in orbit around the Sun"

                How about changing "Sun" to "a star" -- that solves that problem pretty easily.

                The major argument against the present definition is that a planet has cleared its orbital path of space junk. Even the Earth couldn't do that if it was out at the Pluto range. So what would that make the Earth, other than cold?
                I'm not sure, but I think the present definition would make it a dwarf planet. (I have no opinion on this one.)

                The current definition is very inconsistent with reality. We need a better one and it isn't just about funding or the general public.
                Other than the above ("Sun" vs. "a star") I'm not sure how it's not consistent with reality.

                Regardless, there are already many that consider Earth/Moon to be a binary planet.
                I'm not sure why you're back on this topic, since the proposal under discussion makes no mention of the definition of binary planets. In fact, one of the big dogs behind this new proposal (Allen Stern) is of the opinion that the Earth and Moon are a planet / satellite system. (See below)

                No mention in this article of the the Earth and Moon being a binary planet. In fact, it says the opposite:

                "[Allen] Stern said that the definition of a moon is a body that orbits a planet. (The author confesses that he did not think to ask Dr. Stern how he would classify Dactyl, which orbits the asteroid 243 Ida, since neither meets the second criterion of the GPD.) Since all pairs of bodies orbit about their center of mass, i. e., their barycenter, the moon is considered to be orbiting about a planet if the barycenter is located within said planet."

                They then proceed to show that the barycenter of the Earth/Moon system is inside the Earth, i.e. it is planet / satellite system.

                This article says the Earth and Moon are considered a double planet.

                (P.S. Thanks for citing the ESA. It reminded me that they are late on a invoice payment -- time to rattle their cage.)

                This website says the Earth and Moon are both a planet / satellite system and a double planet. In regards to being a double planet, they say this:

                "Definition of a double planet is less clear."

                You cited 3 references to support your position and had 1 win, 1 loss, and 1 tie. Aim higher.

                Comment


                • I have one question for you. How much experience do you have with astronomy in general?
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                  • Originally posted by Evan View Post
                    I have one question for you. How much experience do you have with astronomy in general?
                    I taught introductory Astronomy at the University level, and ran lab courses at the observatory. (Same university as Allen Stern -- we actually started there the same year, but I didn't know him.) Astronomy isn't my field though.

                    Comment


                    • Oohhh, let me get some popcorn! 🍿
                      Last edited by RB211; 02-20-2017, 10:18 PM.

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                      • Originally posted by RB211 View Post
                        Oohhh, let me get some popcorn! ��
                        It's time to pull out the rulers!

                        Comment


                        • Where are the more primitive models? Consider a lone craftsman developing them. Each part is hand made and takes a lot of time to complete. Would he make every one from scratch or would he perhaps incorporate parts from earlier models in the later ones? That would leave the supporting members which would be tossed in the scrap bin to be recycled as smaller parts. And the earlier one completely disappears.

                          As for his tools, they would have been a lot simpler than the mechanisms themselves. So simple that perhaps his wife or helpers would have disposed of them to others who did not appreciate their value when he died. They may have been used for more primitive purposes and worn out doing so. Then they were not copied because other designs may have been more applicable to the other tasks they were being used for. You don't need a dividing head to make a pot or a piece of armor. I can easily see advanced tools being lost to wear and rust when others do not understand them. Just look at E-bay or the "junk" pile outside an abandoned factory today. Or being used as a source of "scrap" metal for making other, simple things by the village blacksmith who had no idea of their original use. One person's precision tool is another's source of material for making nails or pots and pans or horse shoes. What would a cave man do with a micrometer? I doubt he would measure anything with it.

                          The mechanisms themselves were perhaps more amazing and self explanatory. And that may have helped a few of them to survive. Also being "lost" in a ship wreck is a great aid here.



                          Originally posted by Evan View Post
                          I fully agree that it could have been done by one of the ancient Greeks. But the real question is where is the evidence for anyone doing such things? It is hard to believe such a navigational instrument was just a one off project by an ancient highly skilled home shop machinist. There must have been earlier, less complex models to test the feasibility of such a design, and it must have been designed in some way. I would expect to see at least trace evidence of much simpler models in common use at the time. That is how we always seem to do things like this and humans haven't changed much at all over time.

                          That is the real mystery. Why is there just a single high level example?
                          Paul A.
                          SE Texas

                          And if you look REAL close at an analog signal,
                          You will find that it has discrete steps.

                          Comment


                          • Sorry, I have a lot of work to do. I will be doing my presentation and lecture on Friday. Not good for me to distract myself right now. I need to get the 64 channel cap working well enough for the presentation. It has taken this long because plain old red tape. They won't let me work on the computer they bought for me because of "insurance". Like I will somehow electrocute myself on five or 12 volts...

                            I am going to become a paid instructor by this fall so that should change things.


                            Nice to hear you do have some experience. It still doesn't change the reality of the situation. The IAU isn't paying attention to the real experts in the field of planetary science. That is the main problem.
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                            • Originally posted by tomato coupe View Post
                              By this new definition, "moons" would no longer exist.

                              ....
                              Not if they were substantially spherical, at least.

                              Since the definition does not COVER moons, presumably the old definition of a "moon" would continue, but anything which meets the new definition of "planet" would not be one.

                              Any "moon" that is some angular or non-spherical shape would continue to be a moon.
                              CNC machines only go through the motions.

                              Ideas expressed may be mine, or from anyone else in the universe.
                              Not responsible for clerical errors. Or those made by lay people either.
                              Number formats and units may be chosen at random depending on what day it is.
                              I reserve the right to use a number system with any integer base without prior notice.
                              Generalizations are understood to be "often" true, but not true in every case.

                              Comment


                              • Originally posted by J Tiers View Post
                                Not if they were substantially spherical, at least.

                                Since the definition does not COVER moons, presumably the old definition of a "moon" would continue, but anything which meets the new definition of "planet" would not be one.

                                Any "moon" that is some angular or non-spherical shape would continue to be a moon.
                                And presumably in orbit around a planet.

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