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Stargazing Gravity anomaly during solar eclipse.

  1. Jul 28, 2009 #1
    Hi all,

    http://www.newscientist.com/article...best-chance-to-look-for-gravity-anomaly.html"

    the link given above elucidates that the gravity falls during the solar eclipse. I could not understand the logic. Can some one help me in understating the reason for this? why such discrepancy happens only during the solar eclipse why not during the new moon…. If duing the solar eclipse gravity falls then will there be an increase in gravity duing lunar eclipse?
     
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Jul 28, 2009 #2
    In the article I saw no answers to your questions. The article gives me the impression that there aren't really any guesses yet as to why there would be such an anomaly. It looks like a good experiment, though. The rumors of such an anomaly do need to be resolved first, before anybody starts working hard theorizing why there would be an anomaly.
     
    Last edited by a moderator: Apr 24, 2017
  4. Jul 28, 2009 #3
    Well I never told that there is an answer for the anomalies…. This paper just tells that the there is anomalies. I wanted to know why? as it is against my conventional thinking as I see g=Me/r^2

    This leaves me that g should be constant and should not vary with eclipse.
     
  5. Jul 28, 2009 #4
    Are you sure that that formula is correct? I've never come across one like that, the closest I've seen is, g=(mG)/r[tex]^{2}[/tex].
     
  6. Jul 29, 2009 #5
    Well even I meant the same….

    I wanted to write gravity is proportional to mass of earth and inversely proportional to square of its radius.
     
  7. Jul 29, 2009 #6
    This looks more like a Force formula

    [tex]F=\frac{GM_{e}M_{o}}{R^2}[/tex]
    G is universal constant
    Me = Mass of earth
    Mo = Mass of object
    R = Distance BETWEEN both objects as measured from centre to centre

    The GPE equation is similar only its referenced differently. So it is all negative and it is divided by just the distance between objects not the squared distance.
     
  8. Jul 29, 2009 #7
    You have a small force vector from the moon's gravity. You should experience nearly the same effect if the moon was nearly in the same direction of the sun from earth, but not necessarily eclipsing.

    This wouldn't explain the phenomena in the article though. You should just be a bit lighter that day.
     
  9. Jul 30, 2009 #8
    How much lighter?

    One of the article claims it is less by ~8x10^-8 cm/s^2 ; but it will not match up right? Or have I missed some thing…..
     
  10. Jul 30, 2009 #9

    Borg

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    I don't know what the numbers are on this - it's just a thought. Is it possible that the sun's gravitational waves are rippling around the moon resulting in positive and negative wave reinforcement such that it is only strong enough to be observable when you are directly behind the moon with respect to the sun and at just the right distance from the moon?
     
  11. Jul 30, 2009 #10

    Vanadium 50

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    This includes at least four suppositions without any support by data.
     
  12. Jul 30, 2009 #11

    Borg

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    Could you elaborate on what makes this a wrong idea? I really would like to know where I'm not thinking correctly.
     
    Last edited: Jul 30, 2009
  13. Jul 30, 2009 #12
    The gravitational pull of a chunk of mass in china makes it's way through the earth just fine to exert it's gravitational force on you. I wouldn't expect the moon to act any differently.
     
  14. Jul 30, 2009 #13

    F=ma=GMm/r^2

    gmoon = GM/r^2

    G = grav constant
    M = Moon mass
    r = radius of moon's orbit minus earth's radius. I'll plug and chug
     
  15. Jul 30, 2009 #14
    I get 3.8 EE-5 ms^-2, so that's about the same as the number above. They might have used perigee vs apogee.

    That's about 4 millionth's of g.

    So basically nothing.
     
  16. Jul 30, 2009 #15
    http://arxiv.org/abs/gr-qc/0408023" [Broken]

    I doubt the answer is so straight forward. Please look at some of the conventional explanations of anomalous observations during solar eclipses.

    If u think that force of moon has changed the gravity on earth why is that gravity did not increase during lunar eclipse?
     
    Last edited by a moderator: May 4, 2017
  17. Jul 30, 2009 #16
    Without having read the article, is the measured error induced by wishful thinking diminutive to systemic error?

    -but perhaps my question should reside in the social science folder.
     
    Last edited: Jul 30, 2009
  18. Jul 30, 2009 #17

    Chronos

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    Its an old wives tale, nothing gravitationally exceptional occurs during an eclipse. The paper you cite is . . . suspect.
     
  19. Jul 31, 2009 #18
    which website are u talking about….. arxiv.org? I use to think it is a good site…..


    BTW here is one more paper on this issue
    http://adsabs.harvard.edu/abs/2003PhRvD..67b2002V"

    this also some there is some discrepancy
     
    Last edited by a moderator: Apr 24, 2017
  20. Jul 31, 2009 #19
    I believe one suspected cause of the anomaly is due to a reduction in the sun's tidal acceleraton (which is typically on the order of 50 microgals for the sun and 100 microgals for the moon) if the moon slightly attenuates the sun's gravity as the moon comes between the observer and the sun. Tidal acceleration would peak when the sun and moon are overhead, but tidal acceleration might slightly dip compared to that normally expected, and net gravity pull towards Earth's center would increase. During a new moon, without an eclipse, the moon does not come between the sun and observer.

    NASA has been looking into this, but with apparently nothing firm to report.
    http://science.nasa.gov/newhome/headlines/ast06aug99_1.htm [Broken]

    The references in the arxiv article may also be useful. See UnnM01. The NASA reference is also in 0408023.

    At this time, the anomaly is an open issue.
     
    Last edited by a moderator: May 4, 2017
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