Photo courtesy of Space Telescope Science Institute

by Dean Harris and Jonathan Jamieson

Quasars, the most distant objects discovered by astronomers in the Universe, are very bright, large point-like objects just like stars; most are larger than our Solar System, and they radiate enormous amounts of energy. Quasars can be a trillion times brighter than the Sun; they radiate more energy than 100 normal galaxies combined. Quasars are most likely the centers of active galaxies, and may produce their energy from the huge black holes found in the center of the galaxies in which the quasars are located. Quasars drown out the light from all the other stars in the same galaxy because they are so bright.

Quasars look like stars, but are much farther away than stars in our galaxy, and they are much brighter. These are point-like sources of radio waves in space, and are also called "quasi-stellar radio sources"; this name which means star-like emitters of radio waves was first given in the 1960s when quasars were first discovered. Even though they are very far away, the visible light and the strong radio radiation astronomers see shows that quasars must be very bright. As well as radio waves and visible light, quasars also radiate ultraviolet rays, infrared waves, X-rays, and gamma-rays. In 1963 astronomers figured out that these massive objects were about one billion to ten billion light years away. The energy from a quasar takes billions of years to get to the Earth's atmosphere. In 1987, British and American astronomers discovered an object that may be 12 billion light years away.

Bibliography and Additional Sources of Information

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