Effects of a black hole on our solar system

[bdewoody]

The other night on an episode of "The Universe" the subject was black holes and it was mentioned that if even a small black hole passed through our solar system we would most likely be eradicated because of the disruption of the asteroid belt.

That made me wonder how close an average size black hole (if there is such a thing as an average black hole) would have to pass by our solar system to cause havoc. If one passed closely outside the orbit of Pluto wouldn't it alter the paths of many of the objects in the Kuiper belt and senf them hurtling into the inner solar system?

I'm not one to worry about such possibilities as I have many other things closer to home to keep me up at night but it is an interesting subject.

 

[robnissen]

If a BH with a mass similar to the sun passed near Pluto, we would have much more to worry about than asteroids hitting us. A BH of that size could change the orbits of planets, possibly careening one into another, or ejecting a planet from the SS. Human life would not last long once Earth was booted from the solar system. Probably less than a year from when the Earth first was booted from its orbit.

 

[neilsox]

Robnissen is assuming the black hole would linger near Pluto for a few years. At a million kilometers per hour, the black hole would come and go in months rather than years. My guess is most of the orbits would then drift back pretty much as they were, so most humans would survive the changes. We might not even know the black hole had made a visit and be trying to figure out why some of the orbits were changing. If the black hole came closer to Earth and had a powerful accretion disk, we could briefly experience increased atomic radiation and very fast meteors, and a poweful accretion disk would be telescope visable for up to 1/10th light year. Thousands of years would elapse, before comets displaced in the Oort cloud threatened Earth. Asteroid bombardment would peak in a decade or less, but might not be even double, due to a one solar mass black hole a billion kilometers beyond Pluto or Neptune for 4 months. Neil

 

[MeteorWayne]

No, the orbits would be permanently disrupted. Change "black hole" to another star with the sun's mass (since gravitationally, they are the same), and no matter what the speed, every object in the solar system would have it's orbit changed for good.

 

[Couerl]

The BH would likely have a mass higher than the solar system entirely since (as I understand it) the sun isn't quite massive enough to form a black hole to begin with, but let's assume it is the least massive permitted to form a BH. If one came in as close as Pluto and no closer I imagine we wouldn't all go down the drain, but as MW said the orbits would be affected for good and would quite possibly be the end of us. We'd either be tugged out near mars orbit (depending on which side the damn thing was on) or pulled in nearer to the sun if it was opposite us in relation and the outer planets may get ejected or pulled in closer or scooped up altogether depending on where they were during the encounter. Any way I look at it doesn't seem too good for us..

 

[SpaceTas]

The mass of black holes start off around 3.5 solar masses, so typical black hole will be several times the mass of the Sun. So the Sun's path along with planets will veer toward the black hole.

The effects happen on the timescale of the encounter, so months to years. Orbits won't go chaotic with asteroids and planets going every which way. This process takes time, as the one object interacts with the others after the initial disturbance.
You need to do simulations to make any sort of statement. There are lots of orbit simulators out there on the web.
I went and tried out http://phet.colorado.edu/sims/my-solar-system/my-solar-system_en.html. Not necessarily the best but it does the very minimum needed.

I took there sun+planet system, reduced the mass of the planet to 0.001 (reduces Sun's orbit about barycenter to practically nothing i,e Sun stays still when orbit started). Then I added a 4 solar mass black hole (800 units) at a distance of 40 AU (taking planet as earth i.e 6000 units). I increased the accuracy and switched off system centered view (the system now has a black hole off screen).

So with a slow encounter (x velocity 500 units) the Sun starts moving off in little orbits while the "Earth" goes into a large ellipse that probably repeats but it hard to tell.
With a fast encounter (x velocity 5000) the effects are much less: the Sun's path is changes, the Earth's orbit becomes elliptical and stable.

So the upshot is that the planet orbits would become elliptical; then any descent into chaos would be the result of encounters between planets. My guess is that the asteroid belt would be greatly enlarge in extent and the orbits further jumbled by encounters with Jupiter.

The effects on the orbits for the outer planets could be much larger, depending on distance relative to BH path. A highly elliptical Neptune visiting the inner solar system ......

So instead of wild speculation try it out for yourself

 

[neilsox]

When a 5 solar mass star goes super nova, isn't it possible that it ejects 80% of it's mass leaving a one solar mass black hole? Neil

 

[nimbus]

The mass of black holes start off around 3.5 solar masses, so typical black hole will be several times the mass of the Sun. So the Sun's path along with planets will veer toward the black hole.

The effects happen on the timescale of the encounter, so months to years. Orbits won't go chaotic with asteroids and planets going every which way. This process takes time, as the one object interacts with the others after the initial disturbance.
You need to do simulations to make any sort of statement. There are lots of orbit simulators out there on the web.
I went and tried out http://phet.colorado.edu/sims/my-solar-system/my-solar-system_en.html. Not necessarily the best but it does the very minimum needed.

I took there sun+planet system, reduced the mass of the planet to 0.001 (reduces Sun's orbit about barycenter to practically nothing i,e Sun stays still when orbit started). Then I added a 4 solar mass black hole (800 units) at a distance of 40 AU (taking planet as earth i.e 6000 units). I increased the accuracy and switched off system centered view (the system now has a black hole off screen).

So with a slow encounter (x velocity 500 units) the Sun starts moving off in little orbits while the "Earth" goes into a large ellipse that probably repeats but it hard to tell.
With a fast encounter (x velocity 5000) the effects are much less: the Sun's path is changes, the Earth's orbit becomes elliptical and stable.

So the upshot is that the planet orbits would become elliptical; then any descent into chaos would be the result of encounters between planets. My guess is that the asteroid belt would be greatly enlarge in extent and the orbits further jumbled by encounters with Jupiter.

The effects on the orbits for the outer planets could be much larger, depending on distance relative to BH path. A highly elliptical Neptune visiting the inner solar system ......

So instead of wild speculation try it out for yourself

Tiny nitpick. Correct me if I'm wrong, but Jupiter is no less important if you're looking for a close approximation of the fate of Earth in this tourist BH scenario.

 

[SpaceTas]

Yes Nimbus, I left out Jupiter more-or-less deliberately, leaving a bit to the imagination of readers.

No Neilsox. During the supernova it is the core of the massive star that implodes. In most cases this core naturally forms a neutron star (the size/mass of the iron core). This core is just under 1.4 solar masses. There is a mass limit on neutron stars = 1.4 solar mass. To form a black hole extra mass must be added to this core; most likely the explosion is not powerful enough and mass falls onto the core either as the core is covered to neutrons (takes about a second) or a bit latter on. So there is a minimum black hole mass of just over 1.4 solar mass. The actual mass depends on how much extra mass gets entrapped. The lowest mass black hole found (Cygnus X-1) is about 3.5 solar mass. So I picked 4 solar mass in my example.

Stellar mass black holes are very rare, estimates run about 10,000 in the galaxy maybe up to 100,000 compared with 200,000,000 stars

 

[crazyeddie]

I doubt that a black hole passing by at the distance of the orbit of Pluto would seriously disrupt the orbits of the inner planets. At that distance, the sun would have a much stronger gravitational grip than the BH. At worst, the Earth's orbit might become somewhat more elliptical, but there's no way it would be ejected from the solar system. That does not remove the danger of us being bombarded by comets and asteroids, nor does it mean that the outer planets would not be adversely affected. I just think the BH would have to come a lot closer than Pluto for it to destroy the solar system.

 

[nimbus]

Didn't mean to rubbish your input SpaceTas. Just additional suggestion for anyone who didn't know any better and was curious to see as close as possible a rendering of the scenario.

 

[Gravity_Ray]

...That made me wonder how close an average size black hole (if there is such a thing as an average black hole) would have to pass by our solar system to cause havoc. If one passed closely outside the orbit of Pluto wouldn't it alter the paths of many of the objects in the Kuiper belt and senf them hurtling into the inner solar system?...

A black hole is just another star. So to say how will gravity affect something if a black hole gets close to something is the same thing as saying how will gravity affect something if a star gets close to something. Things only get strange if you pass the event horizon.

A black hole that say has 4 times the mass of the sun is just a star with 4 times the mass of the sun (if you are considering gravity). So if a BH goes by our solar system say a few AU outside of Pluto, it will affect Pluto just like any star with 4 times the mass of the sun will do. The solar system will be just fine. I doubt anything will happen to the other planets.

If a star (or black hole) with 4 times the mass of the Sun goes “through” our solar system, then there are software’s that will show you what will happen. It depends on where it passes through, where the planets are located when it passed through, etc...

But just because a black hole goes near something doesn’t mean the end. Gravity will affect you if you get close to ANY star. There is even a school of thought that says you can go "through" an event horizon at an angle and nothing will happen. Only if you have no momentum and "drop" into an event horizon do you get sucked in (so basically you have to be in an accretion disk around the BH to get stretched into spaghetti and all that other visually cool stuff). That’s what an accretion disk is, the matter that is piled up around the BH waiting for its turn to drop in.

Obviously I am not an astronomer so this is my armature thought process and I maybe wrong.

 

[Gravity_Ray]

:lol:
armature amature... whateva

 

[Karl296]

:twisted: Since most stars are part of binary systems, perhaps our sun has a distant sibiling that is now a black hole (of say 3+ solar masses).

 

[SpaceTas]

exactly right gravity_ray. The effects of gravity and hence any disruption to the solar system would be the same no matter the source; star or black hole. So the above discussion would apply if same mass star star made a close pass. There was a recent article and discussion with a star low mass star predicted to have an encounter with the solar system. In that case the mass of the star was less than the Sun and the closest pass much further out than Pluto. So the effects on the planets and asteroids would be even less; smaller resulting eccentricities.

But black holes are more exciting.

The extreme effects of black hole gravity only occur close to the black hole. These effects are the tides (difference in force of gravity) which decline faster than the force of gravity (distance to 3rd power rather than 2). For a stellar mass black hole the last stable orbit is around 10-20 km away from the hole (event horizon about 3 km). So to be ripped apart by a black hole it has to pass very close. Again gravity_ray your instinct is right.

 

[SpaceTas]

Karl296 (you may or maybe not joking) but NO a 3 solar mass black hole anywhere within a light year or so would be detected in effects on planet orbits. The orbits of planets and spacecraft such as the voyagers (now well beyond Pluto) are measured very accurately.

 

[Frederic3]

It wouldn’t take a stellar-mass body to mess up our day. And all our days to come.
A “rogue planet” (if there is such a thing) passing near earth (say 1 million miles) could have one or more of the following effects: 1. Change Earth’s inclination (currently about 23 degrees), resulting in radical climate change. 2) Change Earth’s eccentricity, resulting in radical climate change. 3. Change Luna’s orbit, raising destructively large ocean tides, and possibly triggering earthquakes.
Frederic3

 

[bdewoody]

I wasn't thinking so much about the direct effect that a black hole would have, such as changing the orbit of the inner planets, but more along the line of thought that a lot of objects that are supposed to be Pluto sized or bigger could get jostled about and send a new wave of smaller objects, comet sized zinging into the inner solar system and possibly bombard Earth or Mars.

 

[ToyOne]

Unless my math is off (my algebra is really rusty, as is my physics) a black hole of 3.5 solar masses at a distance from Earth of 1.87AU would exert the same pull as the sun and would cause the Earth to travel in a straight line and fly off into space! Feel free to correct me.

A more fun question: What would happen if a black hole traveling at a million miles per hour collided with the sun?

 

[Zoliv]

Hey,

There's a "game" where you can throw a rogue star in the Solar System and see its effects : http://janus.astro.umd.edu/orbits/nbdy/rstar.html

It's not a black hole, but it's the spirit (though i don't know how accurate this program is).

 

[eburacum45]

The Solar System will have had relatively close encounters with other stars quite a few times over the last four and a half billion years; not close enough to noticably perturb the planets, but I expect the Oort Cloud would have been a bit chaotic for a while, causing comets and perhaps impacts on Earth.

 

[robnissen]

Hey,

There's a "game" where you can throw a rogue star in the Solar System and see its effects : http://janus.astro.umd.edu/orbits/nbdy/rstar.html

It's not a black hole, but it's the spirit (though i don't know how accurate this program is).

Very kewl. Thanks for the link. Earth would get real cold, real fast if an M-class star (.6 solar mass) wondered within 1 AU of the sun. Although at least part of the time, Mars would be right toasty!