attempt by coming to office hours ASAP to discuss the material. You have one week after the due date to improve your score.
Question 38
2 pts
The measurement of cosmic distances was helped tremendously by the discovery, in the early part of the 20th century, that in Cepheid variable stars, the average luminosity was related to:
their parallax
the length of time they took to vary
their radial velocity
their distance from the Sun
the abundance of hydrogen in their atmospheres