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Astronomy

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    $\begingroup$ Might depend on how fast it was going. Typical velocities of nearby stars could be about 100km/s but black holes might be going faster... maybe 1000km/s, if they were accelerated by the supernova explosion that formed them. $\endgroup$
    – James K
    Commented Jul 19, 2021 at 20:32
  • $\begingroup$ @JamesK If a black hole was travelling at that speed, within what time frame would we probably spot it? $\endgroup$
    – A. Kvåle
    Commented Jul 19, 2021 at 20:34
  • $\begingroup$ We would also be able to detect its gravitational effect on other Solar System bodies; their orbits would be perturbed by the black hole’s presence. $\endgroup$
    – Pierre Paquette
    Commented Jul 19, 2021 at 23:38
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    $\begingroup$ When you say the black hole would "arrive" is this the point at which the extra gravitational pull is noticable or the point at which we're within the black hole's event horizon crosses into the solar system? $\endgroup$
    – Lio Elbammalf
    Commented Jul 20, 2021 at 7:15
  • $\begingroup$ @LioElbammalf Depends on what you mean by noticeable. I guess if the effect was noticeable then the black hole would probably be found quite quickly, because people all over the world would want to find out what was causing the mysterious gravitational effects. Both curiosity and fear would probably make a lot of resources be directed at finding the source of the disturbance, which makes me believe that the black hole would be spotted quite quickly. $\endgroup$
    – A. Kvåle
    Commented Jul 20, 2021 at 17:21