Image by NASA's Marshall Space Flight Center via Flickr
Black Holes
What are they?
Strange things happen to a star at the end of its life, as it converts to a red giant, black dwarf, white dwarf, supernova etc. (To know more read Part I of this series.)
Consider a star, having its mass is more than 3 times of the mass of the Sun. At the end of its life, it will collapse and will become more and more compact. This collapse will continue until the star becomes so compact and dense that Nothing…Nothing, not even light , would be able to pass through or escape from its gravity. Hence the star will become dark and it cann’t be viewed directly.
Now we say that our Considered Star is A Black Hole.
Nature and More about Black Holes
As of now, our star is a black hole. Now it will emit strong gravitational waves due to its giant mass-density. These waves will be strongest near the black hole and weakest at last approach of the black hole. Thus the shape of black hole’s effect area, will look like Whirl. This is the same as washing machine whirl. . 
Read Part I of this series Here
