It is the first planet ever discovered to circle a normal Sun-like star. As of Sept. 2001, more than 60 planets have been discovered. The nearest star to Earth known to have a planet is Epsilon Eridani, which is bright enough to be seen with the naked eye. Pulsars are believed to be rapidly spinning neutron stars, so crushed by their own gravity that a million tons of their matter would hardly fill a thimble. Originally thought to be peculiar stars in our own galaxy, quasars are now believed to be the most remote objects in the universe.
Quasars emit tremendous amounts of light and microwave radiation.
Although a number of images show collisions between pairs of galaxies, which could trigger the birth of quasars, some pictures reveal apparently normal, undisturbed galaxies possessing quasars. Quasars are among the most baffling objects in the universe because of their small size and enormous energy output. Quasars are not much bigger than Earth's solar system, but pour out 100 to 1,000 times as much light as an entire galaxy containing a hundred billion stars. A quasar detected in March 2000 with a redshift of 5.8 is 12 billion light-years from Earth and is the most distant object ever observed to date. Most astronomers agree that an active black hole is the only credible possibility that explains how quasars can be so compact, variable, and powerful.