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Thread: can a planet revolve around blackhole?

  1. #1 can a planet revolve around blackhole? 
    precious sir ir r aj's Avatar
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    can a planet revolve around blackhole?
    and what is the safest place for earth in this galaxy?


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    Can a body of life be blinded by what Cleary can only be seen scientifically?


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  4. #3  
    Bullshit Intolerant PhDemon's Avatar
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    Is this some new form of trolling or are you just incapable of making sense?
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  5. #4  
    precious sir ir r aj's Avatar
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    Quote Originally Posted by beingNailed View Post
    Can a body of life be blinded by what Cleary can only be seen scientifically?
    according to my expectation.
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  6. #5  
    precious sir ir r aj's Avatar
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    Quote Originally Posted by PhDemon View Post
    Is this some new form of trolling or are you just incapable of making sense?
    I read this book "50 Greatest Mysteries in the Universe 2012" , then above questiions popped in my mind. sorry
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  7. #6  
    Bullshit Intolerant PhDemon's Avatar
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    Not you, I was referring to beingNailed. Most of his posts sound as though he is a sophomore who has discovered weed and philosophy and gone all Bill and Ted...

    Bill & Ted Are Speechless ''Whoa'' - YouTube

    or he could just be a troll...
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    Quote Originally Posted by beingNailed View Post
    Can a body of life be blinded by what Cleary can only be seen scientifically?
    The next nonsensical post from you will earn a suspension. Weren't you already suspended once for doing this?
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  9. #8  
    Life-Size Nanoputian Flick Montana's Avatar
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    Quote Originally Posted by sir ir r aj View Post
    can a planet revolve around blackhole?
    and what is the safest place for earth in this galaxy?
    When the Milky Way collides with Andromeda, there won't be​ a safe place. *cue ominous music*
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    "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us." -Calvin
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  10. #9  
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    Quote Originally Posted by sir ir r aj View Post
    can a planet revolve around blackhole?
    Yes it could. Far enough from the event horizon the gravitational field of a black hole is indistinguishable from that of a "normal" body of the same mass, so a planet could orbit it according to the usual laws.
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  11. #10  
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    Quote Originally Posted by Markus Hanke View Post
    Quote Originally Posted by sir ir r aj View Post
    can a planet revolve around blackhole?
    Yes it could. Far enough from the event horizon the gravitational field of a black hole is indistinguishable from that of a "normal" body of the same mass, so a planet could orbit it according to the usual laws.
    Thank You for the reply.
    Will Blackhole not pull the planet? It is said that even light cant escape from pull of black hole.
    Anything which black hole pulls inside goes to where? just vanish. But where does it go? I have always wondered.
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  12. #11  
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    Quote Originally Posted by Flick Montana View Post
    Quote Originally Posted by sir ir r aj View Post
    can a planet revolve around blackhole?
    and what is the safest place for earth in this galaxy?
    When the Milky Way collides with Andromeda, there won't be​ a safe place. *cue ominous music*
    So, any suggestions. Please save the earth.
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  13. #12  
    Moderator Moderator Markus Hanke's Avatar
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    Quote Originally Posted by sir ir r aj View Post
    Will Blackhole not pull the planet? It is said that even light cant escape from pull of black hole.
    A planet can follow a stable orbit around a black hole just as it can follow a stable orbit around the sun. Have a look here for a demonstration of such orbits :Wolfram Demonstrations Project

    It is said that even light cant escape from pull of black hole.
    Yes, if it gets too close it won't be able to escape; that doesn't preclude stable orbits though.

    Anything which black hole pulls inside goes to where? just vanish. But where does it go? I have always wondered.
    That is a difficult to answer question; to avoid any unnecessary complication we'll keep it simple and say that the object falls into the singularity, and thus increases the total mass of the black hole.
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  14. #13  
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    Quote Originally Posted by sir ir r aj View Post
    Quote Originally Posted by Flick Montana View Post
    Quote Originally Posted by sir ir r aj View Post
    can a planet revolve around blackhole?
    and what is the safest place for earth in this galaxy?
    When the Milky Way collides with Andromeda, there won't be​ a safe place. *cue ominous music*
    So, any suggestions. Please save the earth.
    There's nothing to be done. Even if Earth should survive the coming together of the galaxies, it won't survive the death of its Sun shortly thereafter.
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    "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us." -Calvin
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  15. #14  
    precious sir ir r aj's Avatar
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    Quote Originally Posted by Flick Montana View Post
    Quote Originally Posted by sir ir r aj View Post
    Quote Originally Posted by Flick Montana View Post
    Quote Originally Posted by sir ir r aj View Post
    can a planet revolve around blackhole?
    and what is the safest place for earth in this galaxy?
    When the Milky Way collides with Andromeda, there won't be​ a safe place. *cue ominous music*
    So, any suggestions. Please save the earth.
    There's nothing to be done. Even if Earth should survive the coming together of the galaxies, it won't survive the death of its Sun shortly thereafter.
    How can we stop the Sun from expanding into a red giant and destroying the Earth?
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  16. #15  
    Universal Mind John Galt's Avatar
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    We have found planets (at least one) around a neutron star, so I don't see why we shouldn't find one around a black hole. sir raj, keep in mind that if the sun suddenly turned into a black hole at 4:00 pm EST this afternoon the Earth's orbit would not change at all.
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  17. #16  
    Forum Professor scoobydoo1's Avatar
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    I'm curious.

    Is there an optimal distance at which a planetary body can orbit a blackhole and not fall into it?
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  18. #17  
    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by scoobydoo1 View Post
    I'm curious.

    Is there an optimal distance at which a planetary body can orbit a blackhole and not fall into it?
    Any distance - it just depends on velocity. As with orbiting any body. (Actually, there is a minimum distance of 1.5 times the radius: within that there are no stable orbits.)
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    ei incumbit probatio qui dicit, non qui negat
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  19. #18  
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    Quote Originally Posted by Strange View Post
    Any distance - it just depends on velocity. As with orbiting any body. (Actually, there is a minimum distance of 1.5 times the radius: within that there are no stable orbits.)
    Thanks. Is there a keyword I can look up for the 1.5 times the radius reference? Also, is the radius that of the blackhole, the planetary body, or...?
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  20. #19  
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    Quote Originally Posted by scoobydoo1 View Post
    Quote Originally Posted by Strange View Post
    Any distance - it just depends on velocity. As with orbiting any body. (Actually, there is a minimum distance of 1.5 times the radius: within that there are no stable orbits.)
    Thanks. Is there a keyword I can look up for the 1.5 times the radius reference? Also, is the radius that of the blackhole, the planetary body, or...?
    Yes, lookup "photon sphere". And it is 1.5 times the Schwarzschild radius (the radius of the event horizon).
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    ei incumbit probatio qui dicit, non qui negat
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  21. #20  
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    Quote Originally Posted by scoobydoo1 View Post
    Is there an optimal distance at which a planetary body can orbit a blackhole and not fall into it?
    Actually, an orbiting body is always in free fall...but that's beside the point here
    You may wish to play around with this simulation : Wolfram Demonstrations Project
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  22. #21  
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    Quote Originally Posted by Markus Hanke View Post
    Actually, an orbiting body is always in free fall...but that's beside the point here
    Meaning that the body will experience a decaying orbit eventually given sufficient time, or have I misunderstood what you meant by "always in free fall"?
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  23. #22  
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    Quote Originally Posted by scoobydoo1 View Post
    Meaning that the body will experience a decaying orbit eventually given sufficient time, or have I misunderstood what you meant by "always in free fall"?
    "Free fall" simply means that there are no external forces other than gravity acting on the body. In GR language - it follows a time-like geodesic in space-time as a result.
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  24. #23  
    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by scoobydoo1 View Post
    Meaning that the body will experience a decaying orbit eventually given sufficient time, or have I misunderstood what you meant by "always in free fall"?
    An orbit is just free fall. It is just that the ground falls away as fast as the orbiting object falls towards it...
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    ei incumbit probatio qui dicit, non qui negat
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  25. #24  
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    Quote Originally Posted by Flick Montana View Post
    Quote Originally Posted by sir ir r aj View Post
    can a planet revolve around blackhole?and what is the safest place for earth in this galaxy?
    When the Milky Way collides with Andromeda, there won't be​ a safe place. *cue ominous music*
    Actually there will be almost no effect on any star. Of the 700 or so billion combined stars, it is estimated that there will be only 6 collisions. The stars are just too far apart. The odds of two stars impacting each other is the equivalent of two bullets being fired into the sky randomly over a 12 mile area colliding. The galaxies will eventually form a common center of rotation. For individual stars the whole process will be a non event.
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  26. #25  
    Universal Mind John Galt's Avatar
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    The "only six collisions" is somewhat misleading. Another star passing us out at the orbit of Pluto would disrupt the orbits of the Earth in a major way. One passing a light year away would trigger an avalance of Oort cloud comets into the inner solar system with resultant extinction event impacts.
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    If the Sun became a Black Hole then Earth's orbit wouldn't be changed in any way, it would keep going around the way it always has been. The Sun would just make a very tiny Black Hole, and Earth would become a frozen ball of rocky ice, but the orbit should stay the same around it as far as I'm aware.

    The mass of the Sun hasn't changed, and therefore the gravity wont have changed. It's just the size (and volume) that's been shrunk by Black Holification.
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  28. #27  
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    Quote Originally Posted by Daecon View Post
    If the Sun became a Black Hole then Earth's orbit wouldn't be changed in any way, it would keep going around the way it always has been. The Sun would just make a very tiny Black Hole, and Earth would become a frozen ball of rocky ice, but the orbit should stay the same around it as far as I'm aware.
    Yes, that is correct. Gravity far away from a source gravity depends mostly just on total mass; it's just when you get closer to the source that you might notice differences.
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  29. #28  
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    Quote Originally Posted by Fossilborealis View Post
    Quote Originally Posted by Flick Montana View Post
    Quote Originally Posted by sir ir r aj View Post
    can a planet revolve around blackhole?and what is the safest place for earth in this galaxy?
    When the Milky Way collides with Andromeda, there won't be​ a safe place. *cue ominous music*
    Actually there will be almost no effect on any star. Of the 700 or so billion combined stars, it is estimated that there will be only 6 collisions. The stars are just too far apart. The odds of two stars impacting each other is the equivalent of two bullets being fired into the sky randomly over a 12 mile area colliding. The galaxies will eventually form a common center of rotation. For individual stars the whole process will be a non event.
    John Galt pretty much said it already, but I'm not thinking about direct collisions.
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  30. #29  
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    Quote Originally Posted by John Galt View Post
    The "only six collisions" is somewhat misleading. Another star passing us out at the orbit of Pluto would disrupt the orbits of the Earth in a major way. One passing a light year away would trigger an avalance of Oort cloud comets into the inner solar system with resultant extinction event impacts.
    Wouldnt it just absorb instantly any closeby comets? Or are you just saying distorted comets' orbits would likely be flung our way?
    If you can't explain it simply, you don't understand it well enough.
    A.E
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  31. #30  
    Universal Mind John Galt's Avatar
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    Why would it do that? The gravitational attraction of a sun mass black hole is identical to that of the sun.
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    Poor wording on my part.I meant if a sun blows through a comet or very close to it, i expect it ll absorb it, rather than reflect it like a pool ball. This star pushing back comets toward earth seems unlikely, doesn t it?Btw, is oort cloud a sphere, or more ring like?Iphone post
    If you can't explain it simply, you don't understand it well enough.
    A.E
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  33. #32  
    Universal Mind John Galt's Avatar
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    If the orbit of Oort Cloud comets are disturbed by a passing star a substantial proportion would be deflected into the inner solar system. The probability of an impact with the Earth would be correspondingly greater, by orders of magnitude, because the number of incoming comets would be so much greater. The Oort Cloud is a sphere.
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  34. #33  
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    I see, I didn't really see it as a sphere, so any outsider body is bound to go through it and is likely to deflect or redirect comets toward the center of the solar system.
    If you can't explain it simply, you don't understand it well enough.
    A.E
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