Like a whirlpool, a black hole swirls around and draws particles of gas, light and dust into itself. The gravitational pull from a black hole is so strong that it can swallow stars, planets and even entire solar systems. Once an object is pulled into a black hole, it can never escape. No one knows for certain what happens to an object once it has been pulled into a black hole. Most stars are grouped into small clusters of two or three stars each.
Binary stars are two stars grouped together that appear to be one star.
There are two kinds of binary stars visual and spectroscopic. Visual binaries are two stars that, when observed with a telescope, actually look like two stars. They revolve around each other very slowly. Spectroscopic binaries are two stars that seem to be one. They revolve around each other quickly.