How do astronomers create three-dimensional maps of the universe?
A)through comparison of computer models of the structure formation with observations
B)by using the position on the sky and the redshift to determine a distance along the line of sight
C)by using the position on the sky and the galaxy brightness as a measure of distance along the line of sight
D)by interpreting the peculiar velocities of each galaxy
E)by carefully measuring the parallax of each galaxy

Question

Quizplus · Accepted Answer

Astronomers typically use the position on the sky and the redshift of a galaxy to determine its distance along the line of sight, creating a three-dimensional map of the universe. This is because redshift provides a measure of a galaxy's recessional velocity and since the universe is expanding, the greater the recessional velocity, the greater the distance a galaxy is from us.

How Do Astronomers Create Three-Dimensional Maps of the Universe