APOD: At the Heart of Orion (2012 Oct 06)

Comments and questions about the APOD on the main view screen.
BDanielMayfield
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Re: APOD: At the Heart of Orion (2012 Oct 06)

Post by BDanielMayfield » Sun Oct 07, 2012 1:33 pm

The danger from a black hole depends upon both it's mass and your distance from it. I think that a safe distance from a 150 solar mass black hole would be an unsafe distance from a supernova.

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Chris Peterson
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Re: APOD: At the Heart of Orion (2012 Oct 06)

Post by Chris Peterson » Sun Oct 07, 2012 2:29 pm

BDanielMayfield wrote:The danger from a black hole depends upon both it's mass and your distance from it. I think that a safe distance from a 150 solar mass black hole would be an unsafe distance from a supernova.
Absolutely true. We'd be perfectly safe right here on Earth (or even on Venus) if the Sun were a 150 solar mass black hole. But to be safe from a supernova you'd need to be tens or hundreds of light years away from it (depending on the asymmetry of the explosion).
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Re: APOD: At the Heart of Orion (2012 Oct 06)

Post by neufer » Sun Oct 07, 2012 8:47 pm

Chris Peterson wrote:
BDanielMayfield wrote:
The danger from a black hole depends upon both it's mass and your distance from it.
I think that a safe distance from a 150 solar mass black hole would be an unsafe distance from a supernova.
Absolutely true. We'd be perfectly safe right here on Earth (or even on Venus) if the Sun were a 150 solar mass black hole.
  • 1) It would be awfully cold.

    2) Our year would be about 'a month' long.

    3) Tides 42 times normal will cause the Earth to phase lock with the Sun.

    4) The moon will have passed beyond the unstable L1 & L2 Lagrangian points
    and have drifted away (perhaps to the stable L4 or L5 Lagrangian points).

    5) Every sun grazing comet will generate an awful lot of "fire works."

    6) Deadly Hawking radiation!
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Re: APOD: At the Heart of Orion (2012 Oct 06)

Post by Chris Peterson » Sun Oct 07, 2012 9:19 pm

neufer wrote:
  • 1) It would be awfully cold.

    2) Our year would be about 'a month' long.

    3) Tides 42 times normal will cause the Earth to phase lock with the Sun.

    4) The moon will have passed beyond the unstable L1 & L2 Lagrangian points
    and have drifted away (perhaps to the stable L4 or L5 Lagrangian points).

    5) Every sun grazing comet will generate an awful lot of "fire works."
All minor secondary effects.
  • 6) Deadly Hawking radiation!
Hardly. The Hawking radiation from a 150 solar mass black hole would have a wavelength of kilometers and a total luminosity on the order of 10-32 watts.

You wouldn't want a lot of dust and gas (perhaps from the outer solar system) forming an accretion disc that might end up producing hard x-rays, but again, that's something entirely secondary to the discussion. The Earth would orbit merrily around this black hole forever without falling into it.
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Re: APOD: At the Heart of Orion (2012 Oct 06)

Post by geckzilla » Sun Oct 07, 2012 9:38 pm

Hmmm, I'm not sure my definition of "perfectly safe" matches up with yours, Chris. I think I'd prefer my consciousness intact and body free of pain. Only having my atoms survive isn't really enough.
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Re: APOD: At the Heart of Orion (2012 Oct 06)

Post by Chris Peterson » Sun Oct 07, 2012 10:22 pm

geckzilla wrote:Hmmm, I'm not sure my definition of "perfectly safe" matches up with yours, Chris. I think I'd prefer my consciousness intact and body free of pain. Only having my atoms survive isn't really enough.
Why would you expect your consciousness to dissolve or your body to be in pain if you were orbiting a 150 solar mass black hole at a distance of 1 AU?
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Re: APOD: At the Heart of Orion (2012 Oct 06)

Post by geckzilla » Sun Oct 07, 2012 10:51 pm

Well, Art made the point about the tidal locking and lack of warmth which I thought might be rather deadly for life as we know it.
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Re: APOD: At the Heart of Orion (2012 Oct 06)

Post by BDanielMayfield » Sun Oct 07, 2012 11:00 pm

Chris Peterson wrote:
BDanielMayfield wrote:The danger from a black hole depends upon both it's mass and your distance from it. I think that a safe distance from a 150 solar mass black hole would be an unsafe distance from a supernova.
Absolutely true. We'd be perfectly safe right here on Earth (or even on Venus) if the Sun were a 150 solar mass black hole. But to be safe from a supernova you'd need to be tens or hundreds of light years away from it (depending on the asymmetry of the explosion).
Thanks for validating my thinking Chris. My point was, what's safer for the preservation of life on planets in the galactic habitable zones of this and other galaxies; a few extra black holes that have eaten up a bunch of stars that would have gone supernova, or no back holes and whole mess of supernova time-bombs. This Orion Black Hole theory has made me look at them in a hole (misspelling intended) new light.

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Re: APOD: At the Heart of Orion (2012 Oct 06)

Post by neufer » Mon Oct 08, 2012 12:19 am

Chris Peterson wrote:
neufer wrote:
  • 6) Deadly Hawking radiation!
Hardly. The Hawking radiation from a 150 solar mass black hole would have a wavelength of kilometers and a total luminosity on the order of 10-32 watts.
The "Deadly Hawking radiation" was a joke, of course.

But there is the additional problem that meteors would be about
10 times more common and 150 times more powerful.
Chris Peterson wrote:
You wouldn't want a lot of dust and gas (perhaps from the outer solar system) forming an accretion disc that might end up producing hard x-rays, but again, that's something entirely secondary to the discussion. The Earth would orbit merrily around this black hole forever without falling into it.
  • King Henry IV, Part i Act 4, Scene 1

HOTSPUR: Come, let us take a muster speedily:
  • Doomsday is near; die all, die merrily.
Merry, a. [OE. merie, mirie, murie, merry, pleasant, AS. merge, pleasant; cf. murge, adv.; prob. akin to OHG. murg, short; cf. L. Murcus a coward, who cuts off his thumb to escape military service; the Anglo-Saxon and English meanings coming from the idea of making the time seem short.]
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