Quasars

What about the spectrum of quasars was so unexpected and surprising? How do we know that they are extremely luminous?

are extremely bright, star like objects that emit various types of radiation, including radio waves.  Quasar’s spectra show very large shifts (0.06 – 5.00), which explain that Quasars are very far away from the earth. The closest quasar (PKS2349) is about 1500 million light years away from the earth. Quasars move at tremendous speed up to 167,000 mph, which is half the speed of light. They emit enormous amount of blue light as well as radio waves and they also are the intense source of X-rays. The fact that quasars can be seen despite their distance proves they are extremely luminous.