The universe is made of stars that emit light and radiation. There are points in the universe that also emit a very intense radiation that appear to be stars, but actually are not. These objects are not easily distinguishable from stars and are known as quasistellar objects or quasars.
As far as scientists can tell, quasars appear to be extremely energetic nuclei of galaxies that move away from us at incredible speeds. The universe is expanding, so galaxies that travel away from us are to be expected. However, what is strange it that quasars seem to be moving much faster than expected.
Using the Doppler effect scientists measures the speed that these galaxies are traveling away from us and were astonished when they found that some of them travel up to 90% of the speed of light. This is even more astounding when you realize that this means that it took the light from the quasar almost 14 billion lightyears to reach Earth, which is about the time when the universe was first born. Quasars give us a glimpse of the state that the universe was in almost at its beginning since it is thought to be only 15 lightyears old. From quasars we can learn a lot about the earliest time of our universe and try to figure out its fate.
Quasars emit their radiation as visible light as well as Rontgen radiation. A typical property of quasars is the variability of their radiation. The intensity of it fluctuate during a period of months, days, hours and even sometimes minutes. Sometimes they disappear completely, like a cloud that has covered up the Sun.
From this variation scientists have determined that quasars are relatively small, the biggest they could be is just as large as the period of light variation (most often only a few light-months or light-days). When we compare this with the sizes of other known galaxies they seem rather small, some galaxies are as big as hundreds of thousands of lightyears. Quasars are thought to be made up of only a limited number of planetary system. To give you some perspective our planetary system which includes the Sun and all the planets is approximately half a light day.
Still they emit extremely intense radiation, they reach luminosities between one hundred and one thousand times that of the brightest galaxies, and often contain between 10 to 100 billion stars. The emission of strong radiation requires very large quantities of energy, the quasars have a yearly consumption of several sun masses of matter. Exactly how and where quasars get this energy is still under debate.
The Beginning of the Universe
Scientists theorize that the quasars may be very large black holes, or possible the nuclei of galaxies where several million supernovas occur. When the universe began there may have been thousands of galaxies like these with superactive stars located in the center but now they have become ordinary galaxies much like our Milky Way. Only the farthest galaxies are still visible, we can still see them in the shape as they were in the early period of the universe. Another theory says that we are observing a prehistoric event of the universe, the unification of matter with anti-matter, even before the galaxy formation took place.