• Question: How strong is the force of a black hole?

    Asked by anon-256336 to Viktor on 3 Jun 2020.
    • Photo: Viktor Doychinov

      Viktor Doychinov answered on 3 Jun 2020:

      I’m afraid I don’t really know, astrophysics is not my speciality.

      From what I understand, as long as you’re beyond the event horizon, the gravitational force of a black hole is more or less the same as that of the star that created it.

      However, I don’t know how accurate this is! I would definitely recommend asking someone else too!

Comments

  • Photo: Susan

    Susan commented on :

    A black hole exerts a gravitational force which – like any other gravitational force – depends on its mass and how far away from it you are. There’s nothing special about a black hole’s gravity: if some alien superweapon were to miraculously collapse the Sun into a black hole, without changing its mass, the Earth’s orbit would stay exactly the same (although it would get very dark!).

    What makes black holes different is that they are very small for their mass: our Sun, collapsed into a black hole, would have a radius of about 3 km, as opposed to its current radius of 700000 km. If we use Newton’s law of gravity (not exactly right near a black hole, but close enough for our purposes), the strength of the gravitational force at the surface of the black-hole Sun would be (700000/3)^2 times the strength of gravity at the surface of the real Sun.

    So, in short, the gravitational force of a black hole is very strong indeed if you are very close to the black hole (an unhealthy place to be), but if you are further away, it is just the same as any other body of the same mass. There is a 4-million-solar-mass black hole in the centre of our Galaxy, but that does not mean that the whole Galaxy is doomed to be sucked into it!