What is the effect of black holes on the Earth? Where do we see black holes?

Black holes have little effect on the Earth. The closest black holes are
many light-years away, and typical black holes are only a few miles
across. If a black hole were to hit the Earth, however, the effects would
be disasterous, with the entire planet being ripped to shreds in a matter
of seconds. Luckily this is extremely unlikely and will almost certainly
never happen.

Black holes are very interesting objects for astronomy. If you want to
know what black holes are and the physics behind them, I'd suggest
reading Stephen Hawking's book "A Brief History of Time". Black holes
cannot be seen directly, but astronomers do see the effects of black
holes. Dust and gas swirling around a black hole heats up as it falls in,
and this hot dust gives off light which we can see. A few binary stars
(two stars in orbit around each other) are orbiting an object which
cannot be seen, but these objects give off lots of x-rays. These "x-ray
binaries" are often thought to house black holes, although some x-ray
binaries may contain other types of stars like neutron stars.

Most galaxies seem to have very massive black holes in their centers. Our
own galaxy has some dark object thaat weighs more than 1 million suns at
its center. Some galaxies have black holes that weigh more than 1 billion
suns! These galaxies often give off extraordinary amounts of light from
their centers as stars are gobbled up by the central black hole. These
quasars are bright enough to bee seen across the entire universe!

I hope this answers your questions, and thank you for writing!

Sincerely,

Kurtis Williams

Back to the Ask An Astronomer page.