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roxmj8 t1_iv35glh wrote

Reply to comment by uniquelyavailable in Closest known black hole to Earth spotted by astronomers by lunarmoonr

Nah a 10 solar mass black hole isn’t a danger to earth at that distance.

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braiam t1_iv3biwq wrote

At that distance, it's not even in the range of our system gravitational forces to affect it.

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ssgrantox t1_iv3qorq wrote

The range of gravity is infinite, but the falloff means that it's effectively zero. But technically, it's not zero

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TehFuckDoIKnow t1_iv3w132 wrote

But it is a zero followed by a decimal point and then a number of zeros but also a non-zero amount of gravity. At least according to the math I can’t do.

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hermenaut t1_iv5ugnc wrote

I've heard gravity propagates at the speed of light.

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humbird_gs t1_iw5dtjr wrote

Not quite infinite. Gravity is limited by the speed of light.

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ssgrantox t1_iwc3mwu wrote

Ok how bout this? What is limit on how far light can travel in a vaccum? Thats the distance limit for gravity.

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humbird_gs t1_iw5drj6 wrote

I still eagerly await tabloid headlines shrieking about the imminent danger of earth being swallowed whole by a black hole.

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f_d t1_iv3uukp wrote

As long as it isn't rapidly closing the distance on a particularly accurate collision course. Which it presumably isn't doing.

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roxmj8 t1_iv3w8om wrote

It would be no different than a 10 mass star.

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f_d t1_iv3ztc6 wrote

Which would also not be something you want barreling straight through the solar system toward the Earth. But those are all extremely unlikely scenarios.

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Mollusc_Memes t1_iv5du5h wrote

And even if it were, we’d have over a thousand years to get out of the solar system. Nobody alive today would ever meet anyone who’d get to meet somebody affected by this black hole.

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f_d t1_iv6l9na wrote

It looks like a microscopic black hole passed through the end of your sentence. But you are still correct.

Barring total societal collapse, humans could probably cobble together some kind of interstellar life raft in the space of a thousand years. Would they be able to evacuate most of the planet to a safe destination? Hard to say for sure. With current technology it would be very unlikely. But at least they would know they needed to get to work on it.

For all we know, there's a deadly asteroid already headed toward us from a blind spot. And the Earth won't support life forever. Distant black holes or not, getting a toehold outside the solar system is a vital step if we want our lineage to continue.

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roxmj8 t1_iv42zo3 wrote

We would already know this is happening, and it’s not. Stars don’t move at the speed of light.

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trevour t1_iv6l81l wrote

Actually, I think you would prefer the black hole since it's smaller and therefore less likely to actually hit us (although even if it didn't hit us it could still rip the earth apart with total forces at a certain distance, although I'm pretty sure the distance is still smaller than the radius of the equivalent star)

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roxmj8 t1_iv6lnyx wrote

If a 10 solar mass object came through our solar system it would tear the whole thing apart. Star, black hole, it wouldn’t matter at all.

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KellyTheET t1_iv53ls6 wrote

Is there a way to detect movement of a black hole? I understand we use the redshift/blueshift of the light emitted by an object to gage their direction, but what if it doesn't emit light?

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f_d t1_iv7bp16 wrote

I am not an astronomer, but this particular black hole has a star orbiting it indicating the position of the hidden black hole. Measuring that star's movement should be straightforward enough. Knowing the location of the black hole but without the companion as a guide, they might also be able to watch for hints of it if it ever passes in front of more distant visible objects. Those hints could be compared over time to see if it was growing larger or smaller relative to us. I don't know what the relative movement of a black hole would do to the shifting of the light bending around it.

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