Minimum safe distance to black hole

In summary, astronomers have found the biggest black holes yet, and as the black holes get bigger, the safe distance gets smaller.
  • #36
feathermoon said:
I'm guessing anything landing in the stable orbits would be completely ripped apart? So the orbits might be filled with rings of matter like a planet?

I guess a slightly more interesting question for me is how big a black hole could pass near our solar system without disrupting our orbits around the sun? Does information on such a scenario?

Here are some numbers to consider in answer to your question. If a three solar mass black hole cruised tangentially by the solar system at a speed of 1000 km per second and at a minimum distance of 2 light years the orbits of the planets would be changed very little in the short term by the presence of the black hole. However, the black hole would have more influence than the sun on Oort cloud objects. Consequenty a large portion of the Oort cloud objects could be captured by the black hole and carried away. The loss of the mass of the captured Oort cloud objects could affect the planet's orbits over a long period of time. The total mass and size of the Oort cloud is conjecture. I don't know any way to estimate the long term effect on the loss of some of its mass on the orbits of the planet's.

Mass of sun 1.99E+30 kilograms
Universal G 6.67E-11
lightspeed 299792458 meters/sec
1 mile = 1609 meters 1609 meters
1 AU = 93,000,000 miles 93000000 miles
1 AU =1609*93000000 meters 1.49637E+11 meters
1 LY = 299792358*365*24*60*60 meters 9.45425E+15 meters
Mass of black hole = 3 solar masses 5.97E+30 kilograms

Acc sun on Earth =GM/R^2 @ R =1 au 5.9284853618E-03 meters/sec/sec
Acc Bh on Earth = G(Mbh)/Rbh) @R =2 ly -1 au 1.1138719171E-12 meters/sec/sec
estimate of delta vel Earth in 10000 yrs 3.5127064777E-01 meters /sec
earth orbital vel sqrt(GM/r) 2.9784572585E+04 meters/sec
centrifugal acc of Earth =v^2/R 5.9284853618E-03 meters/sec/sec
Acc sun on far oort cloud objects 1.49E-12 meters/sec/sec
Acc Bh on far oort cloud objects 4.46E-12 meters/sec/sec
Acc sun on outer Kyper & oort at 55 au's 1.95983E-06 meters/sec/sec
Acc Bh on outer kyper & oort 55 au's from sun 1.11482E-12 meters/sec/sec
 
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  • #37
Tracer said:
Here are some numbers to consider in answer to your question. If a three solar mass black hole cruised tangentially by the solar system at a speed of 1000 km per second and at a minimum distance of 2 light years the orbits of the planets would be changed very little in the short term by the presence of the black hole. However, the black hole would have more influence than the sun on Oort cloud objects. Consequenty a large portion of the Oort cloud objects could be captured by the black hole and carried away. The loss of the mass of the captured Oort cloud objects could affect the planet's orbits over a long period of time. The total mass and size of the Oort cloud is conjecture. I don't know any way to estimate the long term effect on the loss of some of its mass on the orbits of the planet's.

Mass of sun 1.99E+30 kilograms
Universal G 6.67E-11
lightspeed 299792458 meters/sec
1 mile = 1609 meters 1609 meters
1 AU = 93,000,000 miles 93000000 miles
1 AU =1609*93000000 meters 1.49637E+11 meters
1 LY = 299792358*365*24*60*60 meters 9.45425E+15 meters
Mass of black hole = 3 solar masses 5.97E+30 kilograms

Acc sun on Earth =GM/R^2 @ R =1 au 5.9284853618E-03 meters/sec/sec
Acc Bh on Earth = G(Mbh)/Rbh) @R =2 ly -1 au 1.1138719171E-12 meters/sec/sec
estimate of delta vel Earth in 10000 yrs 3.5127064777E-01 meters /sec
earth orbital vel sqrt(GM/r) 2.9784572585E+04 meters/sec
centrifugal acc of Earth =v^2/R 5.9284853618E-03 meters/sec/sec
Acc sun on far oort cloud objects 1.49E-12 meters/sec/sec
Acc Bh on far oort cloud objects 4.46E-12 meters/sec/sec
Acc sun on outer Kyper & oort at 55 au's 1.95983E-06 meters/sec/sec
Acc Bh on outer kyper & oort 55 au's from sun 1.11482E-12 meters/sec/sec
Note this forum's software removed all of the white space from my post and renders if useless.
 
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  • #38
Tracer said:
Note this forum's software removed all of the white space from my post and renders if useless.

Get the spacing correct in Notepad, then copy it here, putting it between code /code tags. Like this:

Code:
A    =          B
 
  • #39
Tracer said:
Note this forum's software removed all of the white space from my post and renders if useless.

Actually, I had no trouble reading it, and thought it was interesting.
 
  • #40
If a three solar mass black hole cruised tangentially by the solar system at a speed of 1000 km per second and at a minimum distance of 2 light years the orbits of the planets would be changed very little in the short term by the presence of the black hole. However, the black hole would have more influence than the sun on Oort cloud objects. Consequenty a large portion of the Oort cloud objects could be captured by the black hole and carried away. The loss of the mass of the captured Oort cloud objects could affect the planet's orbits over a long period of time. The total mass and size of the Oort cloud is conjecture. I don't know any way to estimate the long term effect on the loss of some of its mass on the orbits of the planet's.
The Oort cloud is thought to surround the solar system in a spherical mass extending out to as much as three light years from the sun. If the mass of the bodies in the Oort cloud is evenly distributed around a shell at any given distance from the sun, then the gravitational effects of the mass in that shell will cancel for all other bodies within that shell.
If all of the Oort cloud mass is distributed in this way, then the sun and all planets will be totally unaffected by the Oort cloud. However if the 3 solar mass black hole cruises by the solar system tangentially and at a distance of one light year from the sun, nearly one entire hemisphere of the Oort cloud could be captured and carried away by the black hole. In this case, the sun and the planets would be affected by the half of the mass of the original Oort cloud in the remaining hemisphere. At the very least, the planetary orbits would probably become more eccentric in the long term.
 

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