One of the most interesting, and relatively recently discovered, features of the universe are quasars. Quasars are known for being the most luminous objects in the universe, as well as some of the most massive. In fact, despite being 2.4 x 10^9 light years away, the quasar 3C 273 is still visible with amateur telescopic equipment. But what exactly are quasars? Are they stars, or something quite different?

In short, quasars are something very, very different from stars. Quasars are huge masses of radiation that form at the center of gigantic active galaxies around supermassive black holes. In the most simple of terms, they are formed by the accretion of elements as they are sucked toward a supermassive black hole. On average, quasars are 10 – 10,000 times the size of the black holes they form around. For an artist’s rendering of a quasar, click the link below.

http://en.wikipedia.org/wiki/File:Artist%27s_rendering_ULAS_J1120%2B0641.jpg

First discovered in the 1960s, by the astronomer Allen Sandage, quasars where only evident by the radio waves they emit. Eventually, these radio sources where tied to optical observations of what appeared, at first, to be faint blue stars. However, when spectra were attained of these mysterious objects. The spectra were like nothing ever seen before, with emission lines that defied interpretation. It was not until the 1970s, when accretion disc energy-production was beginning to be understood, that quasars were finally recognized for what they are. Their emission spectra where interpreted as being characterized by massive red shifts, an idea originally proposed by John Bolton in the 60’s.

This red shift is one of the most interesting properties of quasars. Red shifts are shifts in emission spectra caused by the stretching of wavelengths as an object moves away from the observer, or vice versa. This is also known as the Doppler Effect. The implication of the red shift characteristic of quasars is, of course, that the earth and all the quasars around it are moving away from each other. Based on its red shift, the above mentioned quasar, 3C 273 is believed to be moving away from the Earth at about 47,000 km/s. This information was very important at the time of its discovery, as it provided evidence for the theory of an expanding universe, which in turn supported the Big Bang Theory.

Quasars of some of the most interesting known bodies in our universe. These ominously bright objects are unique that can be viewed from billions of light years away with nothing more than an amateur telescope, a single one emitting a thousand times as much energy as the entire Milky Way galaxy.

All information attained from:

http://en.wikipedia.org/wiki/Quasar