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View Full Version : Unlikely Scenarios



Jim Starluck
2008-Jan-31, 06:39 AM
On another forum I lurk about, someone posed a couple of odd scenarios.

Both cases involve a black hole passing "at speed" through our solar system. In one case the gravitational interaction is sufficient to send Earth hurtling off into the void forever. In the other, it somehow slings us into the outer solar system to become the largest moon of Jupiter.

When posted, both scenarios wanted to know how we as a civilization would be able to cope with a hundred years' notice to prepare, but I'm more curious if either scenario is even possible. The latter in particular smacks of "orbital dynamics don't work that way" to me.

Also, some people suggested moving to Mars to escape Earth's fate, but I kinda figured that an event like this would seriously disrupt the orbits of everything in the solar system, from Earth to Jupiter to every random hunk of space rock.

EndeavorRX7
2008-Jan-31, 07:15 AM
Both cases involve a black hole passing "at speed" through our solar system. In one case the gravitational interaction is sufficient to send Earth hurtling off into the void forever. In the other, it somehow slings us into the outer solar system to become the largest moon of Jupiter.

If a black hole passes through our solar system we stand no chance. It's lights out for everyone (pun intended). There is no scenario where a black hole will "sling" earth into Jupiter orbit. And if it were to sling earth towards Jupiter, then where does Jupiter go? Surely it would have gotten slung also being closer and of more total mass.

tony873004
2008-Jan-31, 07:20 AM
If a black hole travelled through our solar system, it could do everything from virtually nothing to expelling Earth and/or all the planets on to interstellar or even intergalactic space. But to put Earth on a trajectory that made it a moon of Jupiter would require two black holes (or other non-black masses) and a scenerio so unlikely that it has probably never happened anywhere in the universe, and probably never will happen anywhere in the universe.

The black hole could pass close to a planet such as Earth and eject it, or it could pass close to the Sun, which would eject all the planets.

Noclevername
2008-Jan-31, 07:27 AM
It depends on what speed "at speed" is; the less time it spends near us the less it effects us. And the size of the BH matters too. The tidal effects of a force strong enough to move Earth to solar-escape velocity in the short time the BH is near us would probably cause massive surface damage. Possibly the Jupiter scenario would, too, though not quite as much.

The best bet for survival in either case is to not be there when it comes. If there's advance warning, we should start building a colony elsewhere. (Mars would be effected, but unless it also has a close pass from the BH it won't be enough to rule it out for homesteading.) If the Earth really is captured by Jupiter, we'll be able to go back, as a frozen earthquake-ravaged Earth is still more conducive to humans than an as-is Mars. Plenty of organics and water, more geothermal sources, etc.



Either scenario is incredibly unlikely. The Jupiter rondezvous is ludicrously unlikely, bordering on plaid. ;)

antoniseb
2008-Jan-31, 09:30 AM
If a black hole passes through our solar system we stand no chance. It's lights out for everyone (pun intended).
That isn't true. I suspect you are thinking that 'through' implies through the center (i.e. through the Sun), which would be troubling, but more in a lights ON kind of way... but a 5 solar mass black hole could pass between the orbits of Neptune and Uranus, and not seriously disrupt the Sun, or Earth's orbit around it. We would probably experience a rain of comets and asteroids which would be difficult to survive, and endure flashes of radiation for which we will be grateful to have an atmosphere, but the inner orbits wouldn't change much.

I agree that moving us to become a Moon of Jupiter is would require some special extra coincidences, such as our Moon passing between Earth and Jupiter near periapsis, and getting ejected from the system, and/or the Earth colliding with Callisto (hard to prepare for).