31.3 & 31.4

Question 1

a large group of stars, dust, and gas; held together by gravity

Answer 1

galaxy

Question 2

spiral galaxy that is about 100,000 light years in diameter and contains from 200 to 400 billion stars, including the Sun

Answer 2

milky way

Question 3

a group of about 50 galaxies including the Milky Way

Answer 3

local group

Question 4

the study of hoe the universe began, what it is made of, and hoe it continues to evolve

Answer 4

Cosmology

Question 5

a theory that about 13.7 billion years ago, the entire universe was contained in a single point that began expanding outward

Answer 5

Big Bang Theory

Question 6

residual radiation from the formation of the universe; predicted by the big bang theory and later detected in 1965

Answer 6

Cosmic Background Radiation

Question 7

type of matter that cannot be seen and can only be detected by its gravitational effects

Answer 7

Dark Matter

Question 8

energy that might be causing the accelerating expansion of the universe

Answer 8

Dark Energy

Question 9

what are the three shapes of galaxies

Answer 9

elliptical, irregular, and spiral

Question 10

What shape is the Milky way galaxy

Answer 10

spiral

Question 11

How many galaxies are in the Local group

Answer 11

50