Lesson Three Topics

Lesson Three Overview
Types of Radiation
Thermal Radiation
Synchrotron Radiation
Planetary Radio Sources
Radio Stars
Radio Galaxies
Quasars
Black Holes
The Milky Way: Our Own Radio Galaxy

	Activities and Quizzes

Lesson Three : Quasars

At first glance, quasars appear to be faint stars. When they were first discovered, astronomers thought they were stars located within our own galaxy. Thus, they were named quasars, short for quasi-stellar radio source. Quasars are actually very distant active galaxies that radiate massive amounts of energy.

Quasars appear very bright because the jet of radiation from the galactic center is pointed right at Earth. Quasars are very unique. They emit an enormous amount of radiation. For instance, the quasar 3C273, the first quasar discovered, radiates 10¹⁴ times as much visible light as the sun! They are the most distant objects in the universe that astronomers have discovered. Some quasars are as far as 15 billion light years away and are moving away from us at 90% of the speed of light. Since quasars are so far away, the image of the quasar that we see on Earth is very old, approximately 15 billion years old! Thus, the quasars that we view were formed shortly after the creation of our universe (which astronomers estimate is a little more than 15 billion years old). Quasars provide astronomers with a lot of information about the universe when it was very young!