One of the main projects being carried out by the Hubble Space Telescope is to measure the distances of galaxies located in groups dozens of millions of lightyears away. What method do astronomers use with the Hubble to find such distances?
A) constructing H-R diagrams
B) measuring the parallax over a period of a decade or so
C) finding Cepheid variables and measuring their periods
D) measuring the x-rays given off by the accretion disks around massive black holes
E) measuring the amount of dust in the disk of the galaxy

Question

Quizplus · Accepted Answer

Astronomers use Cepheid variables located in distant galaxies to measure their distances with the Hubble Space Telescope. Cepheid variables are stars that pulsate regularly, and their period of pulsation is directly related to their brightness. By measuring the period of these stars in distant galaxies, astronomers can determine their distance using the known relationship between period and brightness.

One of the Main Projects Being Carried Out by the Hubble