ch31.3 ch31.4

Question 1

Galaxy-

Answer 1

is a large group of stars,dust,and gas held together be gravity

Question 2

Milky way

Answer 2

some of the stars that you see at night also belong to the milky way galaxy

Question 3

Local group

Answer 3

which includes about fifty galaxies spread out over a distance of 10 million light years across

Question 4

Cosmology

Answer 4

an important discovery about the universe was made in 1929 by the astronomer Edwin Hibble

Question 5

Big bang theory

Answer 5

all matter and energy in the universe were compressed into a single point, which began to expand outward about 13.7 billion years ago

Question 6

Cosmic background radiation

Answer 6

is the residual microwave radiation emitted when the universe was very young

Question 7

Dark matter

Answer 7

is an invisible form of matter that does not emit any detectable electromagnetic energy of its own

Question 8

Dark energy

Answer 8

-is an invisible form of energy that creates a repulsive force causing the universe to expand at a faster rate