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Space Forum / Amateur Astronomy / July 2008Practical astronomy
It is common among empiricists to attribute a variation in the Earth's rotation to so-called tidal friction - http://bowie.gsfc.nasa.gov/ggfc/tides/intro.html Notwithstanding the silly reasoning behind variations in axial rotation using the return of a star to a location using the calendrically based 23 hour 56 min value,would anyone here care to put the depth of the ocean (average depth 2 miles) in context with the Earth's diameter (6 900 miles) using the size of a bowling ball as a gauge (12 inches/215 mm). The idea is to appreciate the power of geodynamics rather than have it subservient to the surface ocean.So,in terms of millimeters or fractions of an inch,how thin is the ocean with respect to planetary diameter in terms of the veneer on a bowling ball ? >The idea is to appreciate the power of geodynamics rather than have it >subservient to the surface ocean.So,in terms of millimeters or >fractions of an inch,how thin is the ocean with respect to planetary >diameter in terms of the veneer on a bowling ball ? Do you think that dragging a 50um film of fluid over the surface of a bowling ball wouldn't have any effect on its rotation? Nonsense. There are good mathematical models of Earth's rotation that demonstrate how both solid-Earth tides and ocean tides contribute to the observed long and short term rotational rate variation. The actual forces that the ocean is able to exert on the Earth are very small, but so is the net effect of those forces. _________________________________________________ Chris L Peterson Cloudbait Observatory http://www.cloudbait.com >>The idea is to appreciate the power of geodynamics rather than have it >>subservient to the surface ocean.So,in terms of millimeters or [quoted text clipped - 3 lines] >Do you think that dragging a 50um film of fluid over the surface of a >bowling ball wouldn't have any effect on its rotation? Nonsense. If the bowling ball was floating freely in space, and if its rotation rate was monitored to millisecond accuracy over several centuries, it could have a noticeable effect. Because I think you agree with me than however small that effect may be, it must still be somewhat larger than zero... >There >are good mathematical models of Earth's rotation that demonstrate how [quoted text clipped - 8 lines] >Cloudbait Observatory >http://www.cloudbait.com  Signature---------------------------------------------------------------- Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN e-mail: pausch at stjarnhimlen dot se WWW: http://stjarnhimlen.se/ >If the bowling ball was floating freely in space, and if its rotation >rate was monitored to millisecond accuracy over several centuries, >it could have a noticeable effect. Because I think you agree with me >than however small that effect may be, it must still be somewhat >larger than zero... Yes, that's exactly my point. Gerald apparently thinks that because the ocean is only a tiny component of the Earth, it can't have any effect. He overlooks the fact that the effect is itself very small, only detectable with extremely precise instrumentation (or very long observation), just like the variation in rotation of a bowling ball would be tiny- but likely detectable- if you applied some viscous force to a thin film of fluid on its surface. _________________________________________________ Chris L Peterson Cloudbait Observatory http://www.cloudbait.com > >If the bowling ball was floating freely in space, and if its rotation > >rate was monitored to millisecond accuracy over several centuries, [quoted text clipped - 13 lines] > Chris L Peterson > Cloudbait Observatoryhttp://www.cloudbait.com I do not overlook facts,I enjoy working with rotational dynamics in a way you can't even imagine,at least not just yet.The idea is to get familiar with rotational dynamics and its effects such as the how rotational geodynamics of the molten/flexible interior causes the Earth to deviate from a perfect sphere and is involved in the motion of the fractured crust.This requires a good appreciation between the relative layers such as crust is to oceanic depth and from there to the enormous rotating interior,an interior which in itself is in a flexible and molten state. In short,you are perfectly entitled to believe that the ocean slows the Earth's rotation down 1 second over a short period but that means you have little appreciation of rotational dynamics and how it generates the planetary profile and subsequently how the geodynamics affects the motion of the thin surface crust. This is how an astronomer thinks in this wonderful era where you mesh evolutionary geology and crustal dynamics with rotational dynamics.The last time I looked,you lot were still working with a geostationary convection cells mechanism for crustal motion whereas I find it easier to work with rotational geodynamics influencing crustal geodynamics. Rather than kill the conversation,consider the relationship of oceanic depth to planetary crustal depth and then look at the rotating molten/ flexible interior,if you stil think the ocean,which is moving with the rotating Earth,slows the planet down then so be it .This is practical astronomy that is closer to home and people can enjoy in the ;long run. Why do you even bother with that nutbar? It's obvious he has the mentality of a flat earth type.! > Yes, that's exactly my point. Gerald apparently thinks that because the > ocean is only a tiny component of the Earth, it can't have any effect. [quoted text clipped - 8 lines] > Cloudbait Observatory > http://www.cloudbait.com > On Fri, 4 Jul 2008 09:06:50 -0700 (PDT), oriel36 > [quoted text clipped - 16 lines] > Chris L Peterson > Cloudbait Observatoryhttp://www.cloudbait.com True, but... Trying to talk sense to Oriel? Not unlike teaching a pig to dance. It just annoys the pig and gets you dirty. My apologies to pigs, most of whom I've met display better manners and more wisdom than Gerald Oriole does. LOL. \ >True, but... > >Trying to talk sense to Oriel? It was a slow day. That said, the subject is interesting, and worth a brief diversion even if there's no hope of Gerald learning anything. Just because a person is himself incapable of learning doesn't mean he can't provide a nice educational opportunity for others. >Not unlike teaching a pig to dance. It just annoys the pig and gets >you dirty. Actually, I expect it's possible to teach a pig to dance. They are pretty smart animals. _________________________________________________ Chris L Peterson Cloudbait Observatory http://www.cloudbait.com > > On Fri, 4 Jul 2008 09:06:50 -0700 (PDT), oriel36 > [quoted text clipped - 32 lines] > > - Show quoted text - I find this amazing,I am the biggest user of time lapse footage and actual images in the group to carry many important points yet I have yet to see people who can understand them much less enjoy them . http://hubblesite.org/newscenter/archive/releases/1999/11/video/b/ The time lapse footage of Uranus and how it orbits the central Sun by using the Equatorial ring as a beacon for how a location responds by changing through 360 degrees over an entire orbit is an wonderful new way to explain the seasons by applying the observation of Uranus to the Earth's orbital motion. So Rod,after disappearing for a year,the only contribution you make is to pass a comment about me when you surely must know that I could not care less ,I am too busy enjoying whjat modern imaging provides and to put that imaging into correct context.I looked at the thread posted by another participant where the contestant of a game show believed that the Sun orbited the Earth ,I do not fault him considering that you and the rest here have shown no aptitude for heliocentric reasoning and how Copernicus figured out the Earth has an orbital motion.You believe in something which is not fit for astronomers - "For to the earth planetary motions appear sometimes direct, sometimes stationary, nay, and sometimes retrograde. But from the sun they are always seen direct" Newton The true astronomer recognises that we see heliocentric orbital motion from a moving Earth and that is the only recognition I care about.So far I have yet to see one person figure out what is right from what is not (Newton) so don't bother talking about me until you get your astronomical facts straight - http://antwrp.gsfc.nasa.gov/apod/image/0112/JuSa2000_tezel.gif So Rod,congratulations on your sole contribution to this newsgroup,I think you have shown the stellar intellectual and intutive qualities in your response and look forward to the high creative qualities which is the mark of an astronomer. > "For to the earth planetary motions appear sometimes direct, sometimes > stationary, nay, and sometimes retrograde. But from the sun they are > always seen direct" Newton > > The true astronomer recognises that we see heliocentric orbital motion > from a moving Earth You seem to be misunderstanding Newton badly. Newton does not claim that the appearance is the reality. Because I don't feel the Earth's orbital motion around the Sun through the soles of my feet, though, I would not know the Earth was moving without the aid of reason. Thus, the appearance of planets moving backwards as the Earth overtakes them, the old geocentric understanding, is a convincing illusion. The true motion that is in one direction is a heliocentric motion - you, yourself, say this. That Newton phrases it in such a way as to appear to imply an "imaginary observer on the surface of the Sun", what of it? How is this a fundamental flaw in his reasoning, or even germane? The beauty that you see in the motions of the planets is all there in the conventional understanding; the time lapse images that you bring to our attention illustrate the actual understanding that Newton gave us of the heavens. That you find it lacking in Newton is because you have not understood Newton. John Savard > > "For to the earth planetary motions appear sometimes direct, sometimes > > stationary, nay, and sometimes retrograde. But from the sun they are [quoted text clipped - 28 lines] > > John Savard I will make this reply an exception for one look at your posting history hardly entitles you to anything other than a convenient mouthpiece for others. "For to the earth planetary motions appear sometimes direct, sometimes stationary, nay, and sometimes retrograde. But from the sun they are always seen direct" Newton Sticking with Newton's approach to and resolution of retrogrades using a hypothetical observer on the Sun put you all in a position that is no better or worse than the contestant in the game show - http://www.maniacworld.com/pitiful-answer-on-game-show.html I have little stomach for the Newton cult these days,I prefer to show what can be enjoyed using the original heliocentric reasoning and a lhealthy approach to the Earth's motions,the new seasonal explanation,geological effects,a cleaerer understanding of clocks and the daily cycle,things like that. If anyone here finds themselves squirming at the game show contestant in respect to heliocentric reasoning ,that is the same position you have from my seat given that nobody can find Newton's silly view incorrect. > put you all in a position that is > no better or worse than the contestant in the game show - Poor guy; obviously general education must be very bad; the 42% of the people who said the Moon, of course, had the right answer. Or perhaps the people in the audience who were polled simply were playing a trick... it is absolutely astonishing that, in this day and age, someone would not know that. Why, it was even astonishing in Sherlock Holmes' day! John Savard > > put you all in a position that is > > no better or worse than the contestant in the game show - [quoted text clipped - 8 lines] > > John Savard People here imagine that you have to look out from the Sun to observethe heliocentric orbital motion of the planets when it is seen perfectly fine from an orbitally moving Earth - http://antwrp.gsfc.nasa.gov/apod/image/0112/JuSa2000_tezel.gif In this day and age with modern imaging that shows the Earth overtaking Jupiter and Saturn,100% of people here who think they are astronomers cannot grasp that basic heliocentric observation so before you feel sorry for the contestant and the other 46 % who thought the Sun orbits the Earth,look at that you believe and then look in the mirror - "For to the earth planetary motions appear sometimes direct, sometimes stationary, nay, and sometimes retrograde. But from the sun they are always seen direct" Newton Remember,however bad you may feel for the contestant in the game show,you are no different in terms of what is correct and what is not,if Newton's silly view of retrogrades means that much to you then soi well and good but personally I prefer modern imaging and the correct reasoning of Copernicus. > People here imagine that you have to look out from the Sun to > observethe heliocentric orbital motion of the planets when it is seen > perfectly fine from an orbitally moving Earth - You are right that it can be seen from the Earth, particularly when we have, now, such things as time-lapse photography to help us. But when photography did not exist at all, or telescopes, and all people had, therefore, were crude records of where the planets were seen, from night to night, among the stars, we could not just see; the heliocentric nature of the Solar System had to be found by reasoning. Since the motion is heliocentric, it is simplest in relation to the Sun. Is that such a terrible thing to say? I don't think Newton meant more than that, in the sense to which you are objecting. > the other 46 % who thought the > Sun orbits the Earth, I thought that was 52%, sadly enough. John Savard > > People here imagine that you have to look out from the Sun to > > observethe heliocentric orbital motion of the planets when it is seen [quoted text clipped - 18 lines] > > John Savard The heliocentric orbital motion of the Earth accounts for the observed behavior of the other planets retrogrades leaving axial rotation to explain the daily cycle,it is an intimate package that is undone by silly views such as hypothetical observers on the Sun. I suggest everyone here take a long and hard look at the guy in the game show for I have looked at the same horror for the last 3 years as the most basic tenet of heliocentric reasoning is ignored for silly and counter-productive junk - "For to the earth planetary motions appear sometimes direct, sometimes stationary, nay, and sometimes retrograde. But from the sun they are always seen direct" Newton Until this is cleared up,there is not an astronomer among you,I do not dictate that,the actual time lapse footage which destroys that base view of Newton does - http://antwrp.gsfc.nasa.gov/apod/image/0112/JuSa2000_tezel.gif > The heliocentric orbital motion of the Earth accounts for the > observed behavior of the other planets retrogrades leaving axial > rotation to explain the daily cycle, On this, we are all agreed. > it is an intimate package that is > undone by silly views such as hypothetical observers on the Sun. And this is where we part company. What is silly about presenting heliocentric motion to the mind in its simplest form, to allow understanding most easily to begin? John Savard > > The heliocentric orbital motion of the Earth accounts for the > > observed behavior of the other planets retrogrades leaving axial [quoted text clipped - 10 lines] > > John Savard Can't do anything for you or the rest here,the guy on the game show has an excuse but nobody here has .There is only one correct answer to the question as to how retrogrades are resolved and it certainly is not this one from the hapless Newton - "For to the earth planetary motions appear sometimes direct, sometimes stationary, nay, and sometimes retrograde. But from the sun they are always seen direct" Newton Having no background in astronomy,the contestant in the quiz show along with 52% of the audience got the most basic Western astronomical fact wrong.I am in the unfortunate position of witnessing 100% failure rate even with actual time lapse footage, the texts of people like Kepler,Galileo and Copernicus himself in support and an audience who thinks they are astronomers. Look at Henri the contestant and it could be a Chris,a Greg,a Sam or a John,all equally wrong and not the slightest bit bothered about it. http://www.maniacworld.com/pitiful-answer-on-game-show.html > > put you all in a position that is > > no better or worse than the contestant in the game show - [quoted text clipped - 8 lines] > > John Savard Regret that I responded to you but no harm done even though it is unlikely to happen again. > would anyone here care to put > the depth of the ocean (average depth 2 miles) in context with the > Earth's diameter (6 900 miles) using the size of a bowling ball as a > gauge (12 inches/215 mm). It is well known that the mountains and oceans of the Earth are extremely tiny compared to the Earth. But then, the variations in the period of the Earth's rotation are also very tiny, only able to be detected now that atomic clocks are available. So it is unclear to me where the contradiction lies. The Earth's diameter is 7,923 miles, so we're talking about .003 inches being the equivalent of 2 miles. (Incidentally, 12 inches is just over 30 centimeters: about 305 mm. It is entirely possible that a "12 inch" bowling ball might actually be exactly 300 mm in diameter, since slide rules and phonograph records, for example, are in such metric sizes.) John Savard > [...] > (Incidentally, 12 inches is just over 30 centimeters: about 305 mm. It > is entirely possible that a "12 inch" bowling ball might actually be > exactly 300 mm in diameter, since slide rules and phonograph records, > for example, are in such metric sizes.) Hmmm, my bowling ball is at home (I'm away at a BBQ) so I can't measure it; Wikipedia to the rescue: <http://en.wikipedia.org/wiki/Bowling_ball> " Regulation ten-pin bowling balls must weigh no more than " 16 pounds (7.2 kg) (governing bodies do not regulate how " light a bowling ball may be) and have a diameter of 8.5 " inches (21.6 cm). On Jul 4, 1:18 pm, "t...@thadlabs.com" <t...@thadlabs.com> wrote: > > [...] > > (Incidentally, 12 inches is just over 30 centimeters: about 305 mm. It [quoted text clipped - 11 lines] > " light a bowling ball may be) and have a diameter of 8.5 > " inches (21.6 cm). Then he was right about how big a bowling ball was in millimeters, even if he had its size in inches wrong. John Savard |
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