11ac1064_ions___Astronomy___Black_Holes__Question
[Date Answered] October 27, 2009 [Questioner (age, location)] Narayanan (India) [Answer] Yes, you are right, it was recently published in the article a href="http://news.bbc.co.uk/2/hi/science/nature/7924414.stm">Dancing black hole twins spotted. From this article I quote, "As matter falls into black holes, it emits light of a characteristic colour that in turn gives information about the direction in which the black hole is moving. In a binary system, two beams should be emitted, each a slightly different colour. The black holes emit two beams, each a slightly different colour Todd Boroson and Tod Lauer of the US National Optical Astronomy Observatory analysed some 17,500 spectra from the Sloan Digital Sky Survey, and have now found just such a pair of emissions coming from a distant quasar." [Question] 
Sir , from this site itself I heard the news of two black Holes orbiting themselves . How does Scientists got information about this ?
Quickie Questions - Astronomy - Black Holes