The term quasar is an abbreviation of quasi-stellar radio source.
When the astronomer Maarten Schmidt examined quasar 3C273 in 1962, he discovered a red_shift of previously unheard-of proportions. According to the Hubble constant, this was an indication of a distance of over three billion light-years. If an object that is so far away can still be detected from the Earth, it must have an incredibly high level of energy.
Hundreds of quasars have been discovered since. Distances of up to 13 billion light-years have been calculated. Quasars are thus the most distant objects discovered in space so far.
Quasars are very active galactic nuclei. Their enormous energy is provided by the accretion of matter, which surrounds the black hole in the form of an accretion disc. It consists matter that is being gathered by the powerful gravitational_forces of the black hole.
The power of gravitation of a black hole increases with its size This means that more and more matter is drawn in from further and further away, which in turn results in an further increase of gravitation.
