I really have to investigate a black hole a billion light years across. Are you sure that was not an estimate of its mass? THey are generally described as being XXXXX times more masive than the sun.

I did some investigation. I think you are refering to the Schwartzchild radius, which is dependent on mass. Also reerred to as the event horizon. Every body in the universe has a Schwazchild radius. The sun's is appx. 3 km and the earth's about 9 mm., both well within the confines of the two. However, when the radius is outside the body, it is a black hole. The radius of the black hole at the center of our galaxy is 7.8 million km.

Sobering, huh?

Ok that was cool...right as I clicked "quote" you finished your edit. I was pretty confused to see the second paragraph:-P

Anywho, it appears again I'm mistaken and should quit drinking whilst posting on PPOT. It's not a black hole, but...just a hole? That appears to be devoid of matter...Specifically, it is *NOT* a black hole.

http://news.yahoo.com/s/space/hugeholefoundintheuniverse;_ylt=AqYC63AOdBKYvY09.E bqS1Nhr7sF

I apologize, again, for the mistake. I'm not doing too well at this lately:-P