In message , Lloyd Parker
writes
In article ,
Happy Hippy wrote:
Lloyd Parker wrote:


Where are all these black holes?


How do you detect one?

You got me.
Exactly. We have to detect them indirectly; by seeing matter falling into one
(the X-rays or gamma rays it emits) or by seeing the perturbations in the
orbit of another star orbiting a black hole. Neither is easy to do from a
distance.

Oh? Cygnus X-1 (one of the best candidates) is one of the brightest
X-ray sources in the sky and it's 2.5 kPc (about 8000 light years) away.
They hope to get a resolved image of the BH at the centre of "our"
galaxy http://www.world-science.net/othernews/051104_blackholefrm.htm