Could a Black Hole Cause a Sunrise in the West?

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Discussion Overview

The discussion revolves around the hypothetical scenario of a black hole passing through our solar system and its potential effects on the perception of sunrise and sunset on Earth. Participants explore the implications of gravitational lensing, the nature of black holes, and the conditions under which such phenomena might occur, including the possibility of optical illusions caused by atmospheric conditions.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that a small moving black hole could create a unique solar eclipse, potentially causing the sun to appear to rise in the west.
  • Others argue that the effects of a black hole would not result in the sun moving to a different part of the sky, suggesting that the phenomenon would not work as described.
  • It is suggested that the gravitational lensing effects of a black hole would not be strong enough to cause significant visual changes in the sun's position.
  • Some participants discuss the possibility of different phenomena being observed simultaneously at various locations on Earth due to the motion of a black hole.
  • There are mentions of atmospheric refraction potentially creating an illusion of the sun rising in the west under specific conditions, though the feasibility of such phenomena is questioned.
  • A later reply introduces the idea that a drastic change in Earth's axial tilt could theoretically cause the sun to rise in different locations, but emphasizes that such an event would require a significant collision with another celestial body.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the effects of a black hole on the perception of sunrise and sunset. There is no consensus on the feasibility of the proposed scenarios, and several participants challenge each other's claims without reaching a definitive conclusion.

Contextual Notes

Limitations include the dependence on specific assumptions about black hole behavior, gravitational lensing effects, and atmospheric conditions. The discussion also reflects uncertainty regarding the long-term stability of Earth's axial tilt in relation to the moon's gravitational influence.

  • #31
Maybe not specifically, but the general idea is that the liquid core is not spinning consistently with the rotation of the Earth, but rather has some additional bulk movement. Exactly why and how is not really known, but given the planet is geologically active, I don't see this to be a shocking phenomena.
https://www.nasa.gov/topics/earth/features/2012-poleReversal.html
 
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  • #32
rootone said:
I think we can agree that the unpredictability of Earth's magnetic poles is weird though,
Is there any mainstream theory which it explains it?

From my astronomy 101 class I learned that much like the sun, the magnetic lines get tangled and break causing the pole swap and that we experience it at a far slower rate than the sun.
 
  • #33
Ashraf Siddiqui said:
I simply want to know probability of sunrise in the west
Get in a rocket ship and fly west at greater than the Earth's rotation rate. Eventually you'll catch up with the sun.

Edit: alternately, wait till sunset and go up a tall elevator. The sun will rise again over the western horizon.
 
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  • #34
snorkack said:
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?
To return to this point: (1) This is 35 arcminutes, or about 4 (temporal) minutes of Earth rotation. (2) Doubling this effect would require increasing the atmospheric density by ~40% [I think, or maybe ~ 100%?] in those 4 minutes of time.

If you see such an effect, it can't be caused by weather. Extreme storms cause atmospheric density to change by ~ 10% over a few hours. So it's presumably caused by a dinosaur-extinction meteoric event.

The corresponding overpressure will travel at somewhat more than the speed of sound (~1000 km/hr), which is just about the Earth's linear rotation speed at mid-latitudes. So it will reach you in less than 4 minutes, and you will die before the second sunset finishes. I hope it's a beautiful one, at least.
 
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  • #35
Ashraf Siddiqui said:
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 ?

Huge mirrors could do it. Maybe 2 mirrors with 1.7 km radius with one orbiting at 380km. You would need to go slightly larger to compensate for any angles. Something much less bright than the Sun could resemble the Sun setting. Also a bent mirror could focus light so something smaller than the Sun's angular diameter could appear just as bright. If you want the pink/purple across the horizon effect you could use an array of small mirrors. Not sure why we would do that. Could also put a mirror on a balloon, tall building, helicopter or mountain and reflect the sunset. There is no need for the mirrors to be in the west.

The town of Rjuken in Norway and Viganella in Italy have a artificial suns in the winter. Should work at sunrise for some part of the year. They are set up to bring in a noon sun.

You can buy lights that make artificial sunrises for an alarm. It is supposed to help you wake up. Here is a mechanical artificial sunrise. You could set that in the north and south side of your room too.

Mar's moon Phobos rises in the west, so does the international space station.

In operation Hardtack Teak the USA detonated a nuclear missile in the atmosphere. At some places on the horizon it would have somewhat resembled a sunrise.

There is also atmospheric effects that cause light to distort or flicker. Stars twinkle. Here is a video of a green flash. I would not say that the sun "rises again" but the edge can go over the horizon and briefly reappear.
 

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