Old stars are poor in heavy elements because there were very few previous generations of stars before the old stars formed.

The elements hydrogen and helium were made during the first few minutes after the big bang.

The center of our galaxy is located in the direction of the constellation of Orion.

Almost every celestial object we see in the sky on a dark, clear night is within the Milky Way galaxy.

Astronomers now speculate that a galaxy’s shape depends on all of the following except

Shapley found the distance to the center of the galaxy by studying the distance to open clusters.

The radio radiation emitted by a radio lobe is mainly synchrotron radiation.

The Milky Way galaxy is an example of a grand-design galaxy.

The redshifts of the galaxies imply that the Universe is expanding and that we are at the center.

Observations of galaxies and clusters of galaxies indicate that about ___________ percent of the matter in the universe is dark matter.