CH 31.3 and 31.4 vocabulary

Question 1

Galaxy

Answer 1

A huge collection of gas, dust, and billions of stars and their solar system. A galaxy is held together by gravity.

Question 2

Milky group

Answer 2

It is a large spiral system consisting of several hundred billion stars, one if which is the Sun.

Question 3

Local group

Answer 3

The group of more than 20 galaxies to which the Milky Way Galaxy belongs. About half are elliptical galaxies, with the remainder being of the spiral or irregular type.

Question 4

Cosmology

Answer 4

Is a branch of astronomy concerned with the studies of the origin and evolution of the universe, from the Big Bang to today and on into the future.

Question 5

Big bang theory

Answer 5

Is the prevailing cosmological model of the observable universe from the earliest known periods through its subsequent large-scale evolution.

Question 6

Cosmic background radiation

Answer 6

Is a faint glow of light that fills the universe, falling on Earth from every direction with nearly uniform intensity.

Question 7

Dark matter

Answer 7

A component of the universe whose presence is discerned from its gravitational attraction rather than its luminosity.

Question 8

Dark energy

Answer 8

Is an unknown form of energy that affects the universe on the largest scales.