Galaxies, Part 1: Crash Course 38

What was the key observation that proved the existence of other galaxies beyond the Milky Way?

• The observation of Cepheid variables in the Andromeda Nebula

• The detection of dark matter in galaxy clusters

What are the four major types of galaxies?

• Elliptical, Spiral, Peculiar, Irregular

• Red, Blue, Yellow, Green

How do spiral galaxies differ from elliptical galaxies?

• Elliptical galaxies are always smaller

• Spiral galaxies have a flat disk and spiral arms, while elliptical galaxies are more rounded

What phenomenon is believed to form elliptical galaxies?

• Supernovae explosions

• Galactic collisions

What is a peculiar galaxy?

• A galaxy with an odd or distorted shape, often due to collisions

• A galaxy with a very regular shape

What are Cepheid variables used for in astronomy?

• To determine the distances to galaxies

• To measure the age of the Universe

What did Edwin Hubble and Milton Humason discover about the Andromeda Galaxy?

• It contained Cepheid variables, allowing its distance to be measured

• It was the largest galaxy in the Universe

What is the significance of galactic collisions?

• They always destroy both galaxies involved

• They can result in the formation of new stars

What are the Large and Small Magellanic Clouds?

• Names of black holes

• Satellite galaxies of the Milky Way

How do astronomers classify galaxies?

• By their overall shape and characteristics

• By their color