Mass of Black Holes?

1. Sep 28, 2006

zero12104

Sorry if this is in the wrong topic area but I'm really wondering this. Would there be any way to measure the mass of a black hole? This is a really interesting thing that I would like to know about. Thanks to anyone that helps!

Last edited: Sep 28, 2006
2. Sep 28, 2006

chroot

Staff Emeritus
Welcome to PF!

There are many ways to measure the mass, and some are deceptively simple.

A black hole of a given mass behaves gravitationally just like any other kind of object with the same mass.

All you need is to do is put a test mass -- say, 1 kg lump of metal -- into orbit around the hole. By observing the lump's orbit, you can calculate the black hole's mass.

You can also use what Nature gives you: stars. By watching the speeds at which stars orbit a suspected black hole, we can estimate the mass of that black hole.

- Warren

3. Sep 28, 2006

zero12104

Thank you vey much for that. I've been looking everywhere and now I finally know and I can ace my report! Thanks!