Could We Detect and Avoid a Black Hole Approaching Our Solar System?

[Chimps]

If a black hole is approaching towards our solar system, at what point could it be detected and is there anything we could do to avoid catastrophe?

Would it make more sense to attempt to move the Earth in such a situation?

 

[Vagn]

We'd see its effects fairly early, as a lot of black holes that would move in such a way are formed in binary systems, and are then accelerated when the second star goes supernova, this allows it to form a 'bow-shaped shockwave' of gas and dust infront of it, which can emit eletromagnetic radiation, we have actually observed these shockwaves before.

You would also see the black hole interact with the Sun's bow-shock, where the stellar wind interacts with the interstellar medium, the gas which would heat up as it approached the event horizon would produce a lot of high intensity radiation, which would be noticed by satellites in Earth orbit.

The black holes gravity could also cause an increase in the number of comets and other Trans-Neptunian Objects heading towards the inner solar system and possibly significant gravitational lensing of background stars.

However, just as interactions between star systems are unlikely, so are interactions with black holes, especially as the majority of nearby stars are small red dwarfs, which would not reach large enough masses to form black holes, so it really isn't worth worrying about.

It would be impossible to avoid such a catastrophe as you would need something of a much larger mass to deflect such an object which would be even more disastrous, but really the chances of such an event occurring are incredibly minute, so it really isn't worth worrying about.

 

[Philosophaie]

The largest supermassive black hole in our Local Group having any possibility of reaching our galaxy is Andromeda. It will not reach even the outskirts for thousands of millions of years.

"What sculpture is to a block of marble, education is to the soul."
Joseph Addison

 

[twofish-quant]

If a black hole is approaching towards our solar system, at what point could it be detected and is there anything we could do to avoid catastrophe?

If you had a one solar mass black hole heading toward the inner solar system, we'd probably detect shifts in the motion of comets and planets, tens of thousands of years before it came close to the earth.

Would it make more sense to attempt to move the Earth in such a situation?

If you can move the earth, you probably could nudge the black hole. In any event, tens of thousands of years would be enough to figure out what to do.

 

[Chimps]

Thanks for the responses.

Although, are we sure to have so much warning even if the black hole is traveling at enormous speed?

What if the black hole is traveling at close to the speed of light? Maybe it has been slingshotted in a violent cosmic event - how much difference could that make?

 

[Vanadium 50]

How many other 100,000,000,000 star-sized objects in the galaxy are traveling near the speed of light? That would be zero.

 

[twofish-quant]

Although, are we sure to have so much warning even if the black hole is traveling at enormous speed?

If it's moving close to c, I'd imagine we'd have even more notice. A one solar mass object traveling through the interstellar medium would likely put out high amounts of detectable radiation as it travels. I'd imagine some sort of x-ray emission shock wave as the ISM hits the magnetic field of the black hole.

Maybe it has been slingshotted in a violent cosmic event - how much difference could that make?

The fasting stars are moving at several hundred km/s. Nowhere near c.

 

[Vagn]

Thanks for the responses.

Although, are we sure to have so much warning even if the black hole is traveling at enormous speed?

What if the black hole is traveling at close to the speed of light? Maybe it has been slingshotted in a violent cosmic event - how much difference could that make?

Such a black holer would have an extremely large, and easily detectable bow-shock in front of it, it would probably also emit a lot of high energy photons, so we should notice it.

 

[Chimps]

Such a black holer would have an extremely large, and easily detectable bow-shock in front of it, it would probably also emit a lot of high energy photons, so we should notice it.

Why would a black hole traveling at huge speed through a vacuum have an easily detectable bow shock?

Why would it emit a lot of high energy photons? Surely it would be the hardest thing to detect in terms of radiation?

 

[Vagn]

Why would a black hole traveling at huge speed through a vacuum have an easily detectable bow shock?

Why would it emit a lot of high energy photons? Surely it would be the hardest thing to detect in terms of radiation?

Because the Solar System is in the dusty disc of the Milky Way, why do you think the Milky way has a dank band across its plane, it isn't a vacuum. This dust would spiral in towards the event horizon, converting gravitational potential energy into high energy photons, so the area around the event horizon would be very hot (well into the millions of kelvin) causing X-Ray and gamma emission.

 

[Chimps]

Because the Solar System is in the dusty disc of the Milky Way, why do you think the Milky way has a dank band across its plane, it isn't a vacuum. This dust would spiral in towards the event horizon, converting gravitational potential energy into high energy photons, so the area around the event horizon would be very hot (well into the millions of kelvin) causing X-Ray and gamma emission.

Okay, that makes sense. So, I guess that it would indeed be very luminous if it was coming at high speed.

Thanks for clarifying that for me.

 

[twofish-quant]

One other way of detecting a black hole is through gravitational lensing. If you have a black hole within say 10 light years of the sun, you'd see stars around the black hole look odd as the black hole bends their light. Also, I'm pretty sure that a nearby black hole would be obvious once you put it in front of the cosmic microwave background.

There is a game that astrophysicists play called "hide the elephant." I'm pretty sure that if you had a 1 solar mass black hole within one light year, it would be obvious. However, if it was 10,000 light years away, it wouldn't be. So the game is to figure out how close the black hole would have to be before you see it.

 

[Chronos]

I would not count on WMAP. It is obviously impossible to precisely subtract effects from the galactic plane from the WMAP signal. WMAP data also excluded measurements from other 'busy' parts of the sky.

 

[Matterwave]

I suppose if the black-hole was traveling at very nearly the speed of light, directly towards us, we wouldn't be able to detect it until it got pretty close because the light or any other signals it had sent out wouldn't reach us until the black-hole itself nearly reached us...but this would require the black hole to have a speed so close to the speed of light...it would be hard to imagine. I wouldn't really worry about such an event...

 

[Vagn]

I suppose if the black-hole was traveling at very nearly the speed of light, directly towards us, we wouldn't be able to detect it until it got pretty close because the light or any other signals it had sent out wouldn't reach us until the black-hole itself nearly reached us...but this would require the black hole to have a speed so close to the speed of light...it would be hard to imagine. I wouldn't really worry about such an event...

You would need an immense amount of kinetic energy for that though. For example for the smallest known stellar black hole (3.8 solar masses) to reach 0.99C you need 4.3E48 joules, which is more than the rest energy of the sun.