Black holes are nothing which has more powerful gravitational force than earth. Due to this gravitational force, any object enters into it will be pulled inside by this gravitational force and can’t escape outside. Even the light which enters cannot escape. Black hole is 10 to 15 times as massive as the sun. Black holes are formed by a larger explosion of a star under goes supernova explosion. Due to this explosion a massive burned out stellar remnant will remain. The remnant will collapse itself. Due to this it becomes ‘0’ volume and infinite density. This is termed as “singularity”. As the density increases the light rays emitted from stars are bent down drastically and wrapped around the stars. Any emitted photon which enters inside this wrap will not leave out side. When a star reaches infinite density light also can’t escape. This termed as “Black hole”. Even a black hole can absorb a huge planet like earth easily. We don’t need to afraid because the closest black hole near the earth was too far from many light years.