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B Solar Eclipse by a Black Hole

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  1. May 1, 2018 #1
    Dear All Concerns

    Black Hole is formed at the end of life of a big star. The mass of such star should be equal to 5-10 solar masses. But I am imaging very small moving black hole coming to our solar system and passing between our earth planet and the sun thereby creating solar eclipse of unique type. In this case the sun may rise in the west once a time and then set again in the west. Is there any possibility of such phenomenon in future?
     
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  3. May 1, 2018 #2

    russ_watters

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    Unless such a black hole passed very close to Earth it would be too small to see much of anything; It would have a diameter of only 30 km. There are calculators for this online.
    Why would you think that? It doesn't sound right.
    Not the way you describe it, no.
     
  4. May 1, 2018 #3
    The speed of moving black hole should be very high as compared to rotational speed of our earth. The black hole would bend the eastern rays of the sun to (derived) western rays of the sun thereby creating an illusion of sunrise in the west.
     
  5. May 1, 2018 #4

    russ_watters

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    No, it wouldn't work that way. What you are describing really doesn't make any sense. It wouldn't look much different from what happens when Mercury passes in front of the sun. It certainly wouldn't appear to move the sun to a different part of the sky.
     
  6. May 2, 2018 #5
    Certainly would not move disc of Sun.

    Mercury does not deflect light that passes its surface. A black hole does.
    However, the angle differs wildly depending on the distance from black hole to the ray being deflected.
     
  7. May 2, 2018 #6
    It means different phenomenons would be observed on different places of earth at the same time e.g. : solar eclipse (night), sunrise in the west, sunset in the east etc. due to constant motion of black hole : If it does happened.
     
  8. May 2, 2018 #7
    It means if it does happened then different phenomenons would be observed at different places on earth at the same time.
    Solar eclipse (night), sunrise in the west, sunset in the east etc. due to constant motion of black hole. Am I right in guessing?
     
  9. May 2, 2018 #8

    davenn

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    your guesses are incorrect
    you were told that in posts #4 and #6

    if you are really interested in astronomy, then you need to start reading up on known science :smile:

    [edit: OT content deleted by mod]
     
    Last edited by a moderator: May 10, 2018
  10. May 2, 2018 #9

    russ_watters

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    Yes, but the sun is pretty much just a bright white featureless blob. A gravitational lens of this would just be a bright ring. So if you superimpose a bright ring over a bright featureless blob it isn't going to look much different. Just a slightly brighter ring but still white and featureless...except as it crosses the edges.

    The direct gravitational effects, however, would be potentially cataclysmic.
     
  11. May 2, 2018 #10

    russ_watters

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    No, gravitational lensing is nowhere near strong enough for that.
     
  12. May 2, 2018 #11
    Please forget what I believe. I simply want to know probability of sunrise in the west. May be some other thing would cause this astronomical phenomenon - An optical illusion would be created by ????
     
  13. May 2, 2018 #12

    russ_watters

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    No phenomenon can cause that.
     
  14. May 2, 2018 #13
    "Bright ring" only on central view.
    If a black hole is off-center, most of the Sun´s disc is very slightly deflected. Only the rays that pass very close to the hole are deflected by large angles.

    Earth atmosphere?
    In normal weather, Sun on horizon is refracted 35 minutes upwards. So that Sun which has just set in West is geometrically 35 minutes under horizon.
    Suppose that some weather phenomenon should cause the refraction to suddenly increase from 35 minutes to 65 minutes. Then Sun would be seen to rise in the west. Of course, Sun would continue setting and the weather phenomenon might also pass, so Sun would set again.

    But do such weather phenomena exist, which might cause the refraction to change so much and so fast?
     
  15. May 2, 2018 #14
    The only event which could cause the Sun to rise in the west would be if the Earth's axis of rotation suddenly flipped to be 180 degrees opposite, (or close to that).
    There isn't any way this can happen other than the Earth colliding with another body of at least similar size to Earth.
    If that happened it would indeed be the end of Earth as we know it.
     
  16. May 2, 2018 #15

    russ_watters

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    The black hole would need to be very close to Earth for it to cover or lens a large fraction of the solar disk. At the Moon's distance it would only cover 1/10 the diameter of the sun's disk(3 arcmin)....while tearing the Earth apart.

    ...but I need to put some time into the calculation for the radius of the ring.
     
  17. May 3, 2018 #16
    What about in the greatly distant future, when the moon has left earths orbit: Wouldn't our axis no longer be bound to one teetering location and make it possible that the earth spins wildly eventually causing the sun to rise in various locations? That is the only time I could think of that it might be possible, but we certainly wouldn't be around to witness it.
     
  18. May 3, 2018 #17
    I think it's accepted as being likely that the Moon assists in making the axis of rotation for Earth quite stable.
    However, lack of the Moon should not induce very rapid chaotic changes of the axis.
     
  19. May 3, 2018 #18

    davenn

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    Why ? yeah, if the Moon suddenly left Earth orbit for some inexplicable reason, it may well reign havoc on Earth
    But that isn't happening, the Moon is just very slowly drifting away, a cm or so a year. So there isn't likely to be
    any cataclysmic change in the way the Earth spins on its axis etc
     
  20. May 4, 2018 #19

    russ_watters

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    Like anything else that moves, a spinning object cannot change its state of motion unless a force is applied.
     
  21. May 4, 2018 #20

    russ_watters

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    I'm curious in what way. Per the above, a spinning object is totally stable if left alone. The moon's influence causes precession; what instabilities would it be combatting?
     
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