Gravity and Celestial Bodies

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Revolution, Apr 29, 2003.

  1. Revolution Registered Senior Member

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    164
    My quest is what kind of event could change the gravity on a planet or moon? Could an asteriod do it? Is it caused by how fast the planet is turning?

    The reason I ask is a theory that the Dino's died off due to a change in the gravity of the planet. Thus why there were much larger. And this 'asteriod' even happened, changed the gravity, and contributed to killing off the ones that actually survived the impact. Like we could not take the pressure at the bottom of the ocean, they were crushed.
     
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  3. blobrana Registered Senior Member

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    If i remember correctly ( it was a long time ago ) , dinosaurs came in all different sizes. Some were the size of rats while others were the size of buildings.

    The simplest answerer to your question is that nothing could change the gravity of the planet.

    But an asteroid collision may indeed have caused their demise; but with the `normal` effects of such an impact such as global cooling etc...
     
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  5. Revolution Registered Senior Member

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    Well I am not so sure, what if we could some how speed the rotation of the planet? What would that do? And the magnetic field of the planet was changed? Not my field.
     
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  7. Beercules Registered Senior Member

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    I think it would depend on what you mean exactly. By change in gravity, do you mean change in strength of the force? Keeping in mind that gravity is the curvature of space-time associated with energy mass, to increase the gravitational strength of something would be a case of increasing it's mass. So it seems that an asteroid isn't likely to increase the mass of the earth enough to crush life out of existence. But someone here will have to clarify that.
     
  8. Revolution Registered Senior Member

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    164
    Well the moon has SOME gravity but not as much as the Earth. How could the moon increase its gravity? Or the Earth decrease its, or vice versa.

    So say you decreased Earth's, and we could all be 'Like Mike' with the big jumps and slam dunks.

    If you are saying Mass, then dont they say the moon was once a part of the Earth? So if some huge disaster happened and the moon broke off into orbit, the mass of the Earth would change, thus changing gravity??

    Or a HUGE asteroid hit the planet, adding mass to the Earth?

    Where is an astro-physicist when you need one.
     
  9. blobrana Registered Senior Member

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    The moon was once part of the earth.

    i believe that a mars sized planet slammed into the earth and the bits of debris got shot into an orbit around the earth, and formed the moon.
    This of course happened very early in the history of the planet when there was fortunately no life on the planet.

    As for gravity destroying the dinosaurs....not in that way...
    I suggest that you do a quick search on google, just type in `demise of the dinosaurs`...

    http://www.nature.com/nsu/010628/010628-15.html
     
  10. kaduseus melencolia I Registered Senior Member

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    213
    In my humble oppinion, heat affects gravity.
    If the planet cooled gravity would increase, but also in my oppinion, if the planet was hotter back then, the cellular structure would have been larger, so if it cooled enough to affect gravity the cellular structure wouldn't have been able to cope anyway.
    The planets are cyclic so with periods of thousands and millions of years you would go through one of the many heating/cooling cycles. Or meteorites.
    One thing about a heat effect on gravity is that the dinosaurs would have been larger with less gravity, their skelatal mechanics would be different, their metabolism and their energy requirements would be different, we would have to rethink the lives of dinosaurs.
     
  11. Blindman Valued Senior Member

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    1,425
    I would like to point out that if the earth did reduce its radius (not mass) the surface gravity would increase but the overall gravity of the earth would not have changed. Just simple Newtonian science, the closer to a body the greater the gravitational attraction.

    There is no evidence of a drastic changing radius for the last 4 billion odd years.
     
  12. Revolution Registered Senior Member

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    164
    So with that and Blind's quote, then it could actually be possible that say durring the jurassic era of the planet there was no moon. And the asteroid theory might of happened and the moon broke away. Thus the diameter of the planet decreased changing the pull on creatures living on the surface.

    I am using this as example of a possible not a probable. So if the moon chunk broke away, the gravitational force on the surface would increase? Is that what you are saying? Or say some trillion year 'thing' happened and the earth shrunk? maybe the core condensed or something?

    If that happened and the diameter went down and just hypothetically saying dino's were there, the gravity could of crushed em, or hindered them soo much they could not survive very long.
     
  13. Blindman Valued Senior Member

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    1,425
    The moon was formed much earlier in the earths history then the Jurassic. The origin of the moon is still just a theory. It is believed that a mars sized body collided with the earth, it did not hit straight on. The glancing blow sent a large amount of debris into orbit around the earth, which eventually coalesced to form the moon. It would have been a spectacular sight. It is also believed that the iron core of the planetoid that hit the earth sunk into the earth and that the moon was created from the lighter mantle. Thus the moon is less dense then the earth. The earth as a result would have grow in mass, radius, and density. Ohh and gravity.
    There must be someone out there that knows the numbers.?

    This moons creation event would have sterilized the earth and destroyed any evidence of life before. You could say it was the day the Earth was born. Dinos still had to wait several billion years before they looked at the moon.

    Gravity changes had nothing to do with the demise of the dinosaurs.

    The earth’s gravity is not even and changes with the inner movements of the earth. We are only just able to start mapping these gravitational bumps, but it requires some of the most sensitive instruments devised by man. The dino’s where not that sensitive.

    The largest dino’s where built like suspension bridges and had hollow bones and could support there entire weight on there hind legs by using there tails as a counter balance.

    At first my reaction was, No way but then I remembered Einstein.
    Only at temperatures so high that the earth would have to be hotter then the sun by many factors. Before it could get so hot it would annihilate its self. It has to do with the fact that the faster an object travels the greater its mass. Temperatures is the expression of the kinetic energy inside an object. Kinetic energy can also be expressed as the speed of movement of the individual atom.

    Im treading on the thin ice I have in my head of Einstein’s theory of relativity, so Ill stop here.
     

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