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Space Forum / Astronomy / July 2006Moon Question
Does the same side of the moon always face the earth, or does the moon rotate and spin around like the earth? Are the classroom models which have the moon stuck on a pole which doesn't spin inaccurate? The craters on the side of the moon that faces earth during a full moon are different from what I can tell. I've looked at a bunch of pictures and the craters aren't in the exact same position in each of them. > Does the same side of the moon always face the earth, or does the moon > rotate and spin around like the earth? Yep, you didn't know this already? It rotates like the Earth, but coincidentally, it takes the same period of time for one rotation, as it takes for one orbit around the Earth, which is why we always see the same side. ----- Kill ratio of Palestinian children to Israeli children 5.7-to-1, Israel's favor. Kill ratio of all Palestinians to Israelis: over 3-to-1. --------- http://www.lrb.co.uk/v28/n06/print/mear01_.html ---------- "Don't worry about American pressure on Israel. We, the Jewish people, control America, and the Americans know it." ---Israeli Prime Minister Ariel Sharon, 2001  SignatureCliff clifffreeling@yahoo.com wrote in alt.astronomy >> Does the same side of the moon always face the earth, or does the moon >> rotate and spin around like the earth? > Yep, you didn't know this already? It rotates like the Earth, but > coincidentally, it takes the same period of time for one rotation, > as it takes for one orbit around the Earth, which is why we always > see the same side. But we don't always see the same side, since the pictures of the full moons I looked at are different. > clifffreeling@yahoo.com wrote in alt.astronomy > [quoted text clipped - 8 lines] > But we don't always see the same side, since the pictures of the > full moons I looked at are different. Make sure the images you are looking at are Earth-based. All of the Earth-based models of the Moon will show pretty much the same configuration of light and dark areas, what is colloquially referred to as the "Man in the Moon". As Mr. Reeling mentions, the Moon is gravitationally locked in a synchronous orbit about the Earth, with one rotation period the same as one orbital period (in fact, if the Moon did not spin, we would be able to see all of its surface over time). This situation of synchronous orbits is quite common among the other planets and many of their natural satellites, and for the same reason. Denny the Moon rotates 27.32 Earth days,and orbits in 27.32 Earth days Thus the moon keeps the same face turned towards the Earth at all times Bert herbertglazier@webtv.net (G=EMC^2 Glazier) wrote in alt.astronomy > Denny the Moon rotates 27.32 Earth days,and orbits in 27.32 Earth days > Thus the moon keeps the same face turned towards the Earth at all times It hasn't always been exactly like that and will change over time though, right? I read that the moon is moving away from earth, so after a few more million years, its orbit around earth will be further out so take longer, right? > herbertglazier@webtv.net (G=EMC^2 Glazier) wrote in alt.astronomy > [quoted text clipped - 5 lines] > after a few more million years, its orbit around earth will be further > out so take longer, right? Yes, but it will still be tidally locked: however long the month becomes, the lunar day will lengthen to match. SignatureOdysseus Odysseus <odysseus1479-at@yahoo-dot.ca> wrote in alt.astronomy >> herbertglazier@webtv.net (G=EMC^2 Glazier) wrote in alt.astronomy >> [quoted text clipped - 8 lines] >Yes, but it will still be tidally locked: however long the month >becomes, the lunar day will lengthen to match. Is that an actual known fact? From one of the last probes they had in orbit around the moon, they know it's weighted on the side facing the earth. so it'll rain as such. SignatureThe Lone Sidewalk Astronomer of Rosamond Telescope Buyers FAQ http://home.inreach.com/starlord Sidewalk Astronomy www.sidewalkastronomy.info Astronomy Net Online Gift Shop http://www.cafepress.com/astronomy_net In Garden Online Gift Shop http://www.cafepress.com/ingarden Blast Off Online Gift Shop http://www.cafepress.com/starlords Astro Blog http://starlord.bloggerteam.com/ > Odysseus <odysseus1479-at@yahoo-dot.ca> wrote in alt.astronomy > [quoted text clipped - 14 lines] > > Is that an actual known fact? > Odysseus <odysseus1479-at@yahoo-dot.ca> wrote in alt.astronomy <snip> > >> It hasn't always been exactly like that and will change over time > >> though, right? I read that the moon is moving away from earth, so [quoted text clipped - 5 lines] > > Is that an actual known fact? Well, it's a prediction based on what we know about the past and present behaviour of the system. Once such a synchronization is established, it takes a major disturbance to break it. A further consequence to be expected is that the Earth's day will lengthen, eventually matching the Moon's rotation/revolution period. SignatureOdysseus Denny what you say could be very right/(why not? They claim the Moon once was 25,000 miles from Earth(I think 50,000) so you can see its orbit has been getting bigger and bigger. I have a theory based on good science that this is true of all orbiting objects. bert Good science? No, total BULLSHIT, BEERTbrain! Saul Levy >Denny what you say could be very right/(why not? They claim the Moon >once was 25,000 miles from Earth(I think 50,000) so you can see its >orbit has been getting bigger and bigger. I have a theory based on >good science that this is true of all orbiting objects. bert Saul Levy <saullevy1@cox.net> wrote in alt.astronomy One of the shows I watched on science channel reported that the moon was closer in the past and appeared a lot bigger in the sky. I'm not sure it was as close as 25,000 miles, though. I don't see a problem with it moving further away, though, so what's your beef with the idea? From what I understand, they put a mirror on the moon and can bounce a laser beam off it and measure the current distance, and it shows that it's moving away from us. >Good science? No, total BULLSHIT, BEERTbrain! > [quoted text clipped - 4 lines] >>orbit has been getting bigger and bigger. I have a theory based on >>good science that this is true of all orbiting objects. bert > Saul Levy <saullevy1@cox.net> wrote in alt.astronomy > [quoted text clipped - 14 lines] >>>orbit has been getting bigger and bigger. I have a theory based on >>>good science that this is true of all orbiting objects. bert Saul is not quibbling with the first 2 sentences in bert's reply (well he might be with those too but..). He is quibbling with the phrase in the last sentence "based on good science". Bert uses scientific words in his grammatically poor postings, but has demonstrated no clue of real scientific knowledge or process. He waves his hands and assumes everyone will see he is correct. But to most of us, he simply adds to the noise level in the group rather than the signal. > > Saul Levy <saullevy1@cox.net> wrote in alt.astronomy > > [quoted text clipped - 22 lines] > everyone will see he is correct. But to most of us, he simply adds to > the noise level in the group rather than the signal. Now you let the cat out of the bag! OJ Scott My bad grammar is a known fact by now. It was worse. I'm a very careless writer,and feel bad about that. I try to make up for it for making my posts interesting and my love of good science. You like Saul and others try to bring me down. like saying that 61 Jupiter moons are wrong and its 63 because you said so,and its in Google. I'm laughing as I just typed that. Still Scott I can live with you. Try to understand where I am coming from(at least once) Bert Nice reference to nothing there, BEERTbrain! Why didn't you reply to something Scott or I actually said? Saul Levy >Scott My bad grammar is a known fact by now. It was worse. I'm a very >careless writer,and feel bad about that. I try to make up for it for [quoted text clipped - 3 lines] >I just typed that. Still Scott I can live with you. Try to understand >where I am coming from(at least once) Bert > Scott My bad grammar is a known fact by now. It was worse. I'm a very > careless writer,and feel bad about that. I try to make up for it for [quoted text clipped - 3 lines] > I just typed that. Still Scott I can live with you. Try to understand > where I am coming from(at least once) Bert From what I have observed, you reject good science out of hand, not by demonstrating it is bad but simply because you don't like it (or it doesn't fit in with your personal world view). To quote one of the authors in the textbook I will use in my class this fall, "Returning to our early discussion of what science is and how science works, the story we tell here is one that many people have 'tried to prove wrong,' but which has withstood all the tests ... so far." When I read that passage, I immediately thought of you and some of the others here that contribute to the noise level in this group, rather than the signal. The message is simple - if you think the science is bad, prove it (as others with scientific backgrounds have done). Waving your hands in the air and claiming it is bad simply does not hold water. Scott We are here to view the universe. We don't all see it the same way. GR conflicts with QM I conflict with Google many times. My theories and those of others are not carved in stone(like the 10 commandments) Reality is the capture theory I read,and as you know is in many books. Even Einstein had bad theories. Humankind has its Gods(religions),and that theory is a killer. I like the BB theory, I like multi-universes theory, I like black holes. I like inertia and gravity being the same thing. I like the string theory. I like extra dimensions. I like my concave and convex theory. My critical mass theory. My time lapse theory. I like that I can produce pulse fusion and contain it. Can take pictures a million times faster than Eddington's strobe light. That the universe gave me a long spacetime so I can view it,and give answers to some of its mysteries. Bert You conflict with SCIENCE, BEERTbrain! That's the bottom line. Saul Levy >Scott We are here to view the universe. We don't all see it the same >way. GR conflicts with QM I conflict with Google many times. My theories [quoted text clipped - 9 lines] >Eddington's strobe light. That the universe gave me a long spacetime so >I can view it,and give answers to some of its mysteries. Bert Saul You only have a bottom line.and that is why you have to post on top. No body is really interesed in a low wit thinker. You are to dense to reasize this. Silly for me to tell you to get "lost" You are Saul the lost witless person in the wilderness. You walk in the hot desert of Arizona looking for clams.that are in the mirages you see in every around you. Best to keep in mind saul that clams are not kosher Bert I hate seafood, BEERTbrain! It all stinks! Saul Levy >Saul You only have a bottom line.and that is why you have to post on >top. No body is really interesed in a low wit thinker. You are to dense [quoted text clipped - 3 lines] >around you. Best to keep in mind saul that clams are not kosher >Bert > Scott We are here to view the universe. We don't all see it the same > way. GR conflicts with QM I conflict with Google many times. My theories [quoted text clipped - 9 lines] > Eddington's strobe light. That the universe gave me a long spacetime so > I can view it,and give answers to some of its mysteries. Bert The point is, just because you think a theory is wrong does not make it so. It is to be proved wrong and as I continue to point out, to date, no one has successfully shot down the collision-ejecton theory. And it is not for lack of trying. As to your collection of "theories" you exaggerate a bit there. You have ideas, but have not tested them or presented them in ways that can be tested. They fail as theories on that alone. And yes, in science, semantics is important. Scott Not all theories can be tested. All theories are open for discussion. The big bang theory I like but many don't String theory has never been tested,and I like it. QM theory has meet every test and yet people go against it.Ask nightbat or Double-A if they like BH Once a theory has shown to be reality the person that came up with the theory has a good chance for a Nobel. I have proven my lapse time theory using my fast photography. I'm waiting for my Nobel Bert PS You seem to be mellowing(no nasty personal remarks) > Scott Not all theories can be tested. All theories are open for > discussion. The big bang theory I like but many don't String theory has [quoted text clipped - 4 lines] > using my fast photography. I'm waiting for my Nobel Bert PS You > seem to be mellowing(no nasty personal remarks) I frankly have no concern about nonscience people liking or disliking a particular theory. String theory is considered by quite a few in the scientific circles not to be a theory as it does not provide testable predictions. On the other hand, the big bang model and QM have made predictions and have been vindicated each time. They are good science simply because they do provide for testable results. Are they the final answer? Not likely. But so far, no experiment proposed to disprove either has been found. And, as to your own "theory", I assume you have published it in some recognized peer-reviewed journal. Else you have not even made the first step toward getting a Nobel (or any other) Prize. Black Holes are NOT theories, they can be found and their effects studied. SignatureThe Lone Sidewalk Astronomer of Rosamond Telescope Buyers FAQ http://home.inreach.com/starlord Sidewalk Astronomy www.sidewalkastronomy.info Astronomy Net Online Gift Shop http://www.cafepress.com/astronomy_net In Garden Online Gift Shop http://www.cafepress.com/ingarden Blast Off Online Gift Shop http://www.cafepress.com/starlords Astro Blog http://starlord.bloggerteam.com/ >> Scott Not all theories can be tested. All theories are open for >> discussion. The big bang theory I like but many don't String theory has [quoted text clipped - 17 lines] > recognized peer-reviewed journal. Else you have not even made the first > step toward getting a Nobel (or any other) Prize. > Black Holes are NOT theories, they can be found and their effects studied. > > -- > The Lone Sidewalk Astronomer of Rosamond Only objects with high gravitational fields have been found, not necessarily black holes. There are other theories. Gravastars http://www.space.com/scienceastronomy/astronomy/gravastars_020423.html Dark Energy Stars http://www.newscientist.com/article.ns?id=mg18925423.600&feedId=online-news_rss20 Even Stephen Hawking no longer holds with classical black hole theory, now stating that whatever goes into a black hole will come out again someday. http://pancake.uchicago.edu/~carroll/hawkingdublin.txt If information can re-emerge from a "black hole" as Hawking now asserts, then a black hole singularity can never form, because that singularity would destroy all information. Double-A > Black Holes are NOT theories, they can be found and their effects studied. Science is not about making absolute statements. As I point out to my classes, the best we can say on the subject is that there are objects that we cannot see because of great distances between us and them that behave the way our current gravity theories say a black hole should behave. But since these current gravity theories have their limits, it has not been demonstrated that the prediction of or properties ascribed to black holes is not one of those limits. Scott A theory to me is a plan or scheme existing in the mind only(in the beginning). In time if it fits well with reality it will be proven by experiment,or observation. We can hopefully hypothesis an explanation to account for any phenomenon. All my theories,ideas,hypothesis,and every description of stuff I have given out to the world through my webtv. They are discussed all over the world. (the better ones) I love science I love mechanics. I* love to improve on all machinery,and find out how every thing works. I know I'm not to smart because that gyroscope I got 70 years ago still holds mysteries for me. Prescession is tricky Bert > Scott A theory to me is a plan or scheme existing in the mind only(in > the beginning). In time if it fits well with reality it will be proven [quoted text clipped - 6 lines] > not to smart because that gyroscope I got 70 years ago still holds > mysteries for me. Prescession is tricky Bert Then my suggestion is to not use the word theory in any discussion involving science because it has a precise meaning in science akin to successes in experimental and observational results, and are no better than that last set of successful tests. It is a very black and white definition, unlike your use of the word. Scott There is nothing black and white about a theory. The super-string theory must tell you that. Tell me what part is it white and what part is black. Scott you are 100% wrong. Theories are not precise. Nothing is precise. The best one word to describe a theory is the word "Scheme" Bert PS I hate the word "precise" for we know we can only come up with approximation. > Scott There is nothing black and white about a theory. The super-string > theory must tell you that. Tell me what part is it white and what part > is black. Scott you are 100% wrong. Theories are not precise. Nothing > is precise. The best one word to describe a theory is the word "Scheme" > Bert PS I hate the word "precise" for we know we can only come up > with approximation. I never said theories were precise. I said they were a collection of successfully tested hypotheses. "Tested" in the key word here, and successfully tested a requirement. If we apply that standard to string theory, it fails. The onus is on string theorists to contrive testable hypotheses before they can advance to the level of "theory" in the scientific parlance of the word. That definition is black and white, and it is a razor that can be used to cut away poor ideas from those more likely to be correct, precisely because they can be successfully tested. If you'd learn some physics, you understand precession, which you obviously can't spell either, BEERTbrain! Saul Levy >Scott A theory to me is a plan or scheme existing in the mind only(in >the beginning). In time if it fits well with reality it will be proven [quoted text clipped - 6 lines] >not to smart because that gyroscope I got 70 years ago still holds >mysteries for me. Prescession is tricky Bert BEERTbrain's prize will be for STUPIDITY! Saul Levy >> Scott Not all theories can be tested. All theories are open for >> discussion. The big bang theory I like but many don't String theory has [quoted text clipped - 17 lines] >recognized peer-reviewed journal. Else you have not even made the first >step toward getting a Nobel (or any other) Prize. Very good, Scott! You got it right! Saul Levy >> Saul Levy <saullevy1@cox.net> wrote in alt.astronomy >> [quoted text clipped - 22 lines] >everyone will see he is correct. But to most of us, he simply adds to >the noise level in the group rather than the signal. > Saul Levy <saullevy1@cox.net> wrote in alt.astronomy > [quoted text clipped - 5 lines] > can bounce a laser beam off it and measure the current distance, > and it shows that it's moving away from us. Whenever the planet rotates faster than its moon revolves (as is the case with Earth), momentum is transferred to the moon through tidal forces and it will move further away, while the planets rotation slows down. When the moon revolves faster than the planet rotates, the moon will move closer and the planet's rotation rate will increase. Double-A What are you replying to, Denny? You have to understand that BEERTbrain doesn't know what good science is. Saul Levy >Saul Levy <saullevy1@cox.net> wrote in alt.astronomy > [quoted text clipped - 14 lines] >>>orbit has been getting bigger and bigger. I have a theory based on >>>good science that this is true of all orbiting objects. bert > Does the same side of the moon always face the earth, or does the moon > rotate and spin around like the earth? Yes. ;) Seriously, the Moon does rotate on its axis, but due to a phenomenon called "tidal locking" its rotational period is exactly the same as its period of revolution, the time it takes to orbit the Earth. As a result it always shows us the same face and, conversely, from a given location on the Moon the Earth will always be seen in just about the same place in the sky. > Are the classroom models which have the moon stuck on a pole which > doesn't spin inaccurate? The craters on the side of the moon that > faces earth during a full moon are different from what I can tell. Some of the Full Moon's features appear changed in comparison to the partial phases, because sunlight is then being reflected directly back at us, while at other times the illumination is more oblique. For one thing, where there's surface relief there'll be shadows that vary in length according to the local altitude of the Sun. For another, various surface materials and textures can change in appearance as their light-source moves as an effect of selective absorption or scattering. The enormous "ray systems" that surround some of the larger craters, for example, are most apparent within a day or two of a Full Moon. > I've looked at a bunch of pictures and the craters aren't in the > exact same position in each of them. As someone else suggested, make sure they were all taken from Earth! However, since the Moon's orbit isn't perfectly circular, its position isn't perfectly in synch with its rotation all the way around--it just averages out that way. So it does appear to rock back and forth over the course of a month (the technical term for the motion is "libration"), exposing a little more of the leading limb and less of the trailing at one time, and the converse around two weeks later. The difference between the views is not great, but it's certainly enough for the observant to notice in photos, as you apparently have done, and for moon-watchers to take into account when planning observing sessions. Moreover the tilt of the Equator WRT the plane of the Moon's orbit lets us see a little more of the north limb at some times, the south limb at others. Finally there's parallax to consider: observers in the Arctic (or Antarctic), and observations made near moonrise (or moonset), will have a slightly different angle of view from those at the Equator, and when the Moon is at its highest, respectlvely. There's still something like 45% (?) of the Moon's surface that we never even glimpse from Earth, and that deserves the designation "the far side of the Moon". SignatureOdysseus |
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