When studying the optical spectrum of a very distant quasar (quasi stellar object), they found that...
Quasars are faint, distant sources of radio waves. (Quasar is short for "quasi-stellar source." They are so named because, like a star, they appear to the astronomer to be pointlike.) From the shift in the frequency of their emitted light toward the red, called the "redshift," we know that quasars are moving very fast. Astronomers observe that the more distant an object is from the earth, the faster it moves. In this way they determine that quasars are billions of...
Some observations reported on an astronomical object (quasar 3C-9) suggest that, when it emitted the light that has just reached the earth, it was moving away from the earth at a speed of about (4/5),c (a) One of the lines identified in its spectrum has a wavelength of about 1200 A when emitted from a stationary source. At what wavelength must this line have appeared on the observed spectrum of the quasar? (Note: 1 Å= 10-10 m and c =...