It's really fun to keep observing with night sky with your naked eyes or a telescope. But have you ever thought that their might be bodies which could not be seen? Well let us think, what is Vision?
When light is reflected or emitted by an object and it comes to our eyes, we can see that thing. According to the Interference phenomena and the Photoelectric Effect, light can be categorized as both a wave and particle. Also called as the Wave-Particle Duality of light.
Let us consider a quantum of light with some mass. So, if light passes through a very heavy body with a really powerful gravitational field, the path of light might bend and it might be absorbed if the body's gravitational field is stronger. So such bodies might be called 'invisible' or black-bodies. Now, these bodies are popularly called Black holes. These considered existing in theoretical physics but there is no experimental proof of their existence.
A Black hole is born when a huge supernova collapses under its own gravity. Technically, A black is considered to be A region in space-time from which nothing, not even light can escape. You might think that if the black hole absorbs all kinds of radiation, it might possible not emit any too. But Stephen Hawking did a good piece of thinking on that concept and came up with the idea of the popular Hawking Radiation. He came up with this idea when his fellow student Jacob Bekenstein suggested that a Black hole should have a finite non-zero temperature and entropy and Black holes must emit some kind of radiation, Hawking radiation states that 'Close to the event horizon of a black hole, a local observer must accelerate to keep from falling in. An accelerating observer sees a thermal bath of particles that pop out of the local acceleration horizon, turn around, and free-fall back in. The condition of local thermal equilibrium implies that the consistent extension of this local thermal bath has a finite temperature...