If a black hole were to wander into our solar system, the consequences would depend significantly on its mass and proximity. Here are the potential scenarios:
Primordial Black Holes: If a small primordial black hole passed through the outer regions, such as the Oort Cloud, it could cause minor gravitational disturbances, potentially nudging some comets into the inner solar system
This might lead to an increase in cometary activity but would likely have minimal direct effects on Earth or other planets
Stellar-Mass Black Holes: A larger black hole, especially one similar in mass to the Sun or greater, could have catastrophic effects.
If it approached within about 100 astronomical units (beyond Pluto), it could begin altering the orbits of outer planets like Uranus and Neptune
As it got closer, Earth could experience dramatic gravitational shifts, possibly leading to changes in climate and even geological upheaval, such as increased volcanic activity
The likelihood of such an event is exceedingly low given the vast distances between celestial bodies in our galaxy