Astronomy B - Unit 3: Galaxies

A galaxy is _____.

• where the Guardians are from

• a cloud of gas and dust in outer space

• a massive and extremely remote celestial object, emitting exceptionally large amounts of energy

• a large group of stars, dust, and gas, in space held together by gravity

Galaxies are so vast that we measure the distance across them in ____.

• googolmeters

• lightyears

• astronomical units

• kilometers

What is believed to dominate center of most galaxies?

• quasars

• red supergiant star

• supermassive black hole

• supermassive neutron star

What did early astronomers believe galaxies were?

• Collision between two massive stars

• Nebulas associated with the Milky Way

• Collision between two supermassive black holes

• Remnants of dead stars outside of the Milky Way

What are the 3 main classes of galaxies? (select all that apply)

• elliptical

• spindle

• irregular

• spiral

Hubble's Classification Scheme is often called _____.

• Hubble's Spear

• Hubble's Tuning Fork

• Hubble's Scythe

• Hubble's Pitchfork

In terms of galactic age, galaxies that are very young and just forming are _____ in shape.

• elliptical

• irregular

• spiral

In terms of galactic age, galaxies that are young and have lots of star formation are _____ in shape.

• elliptical

• irregular

• spiral

In terms of galactic age, galaxies that are old and have little to no star formation are _____ in shape.

• elliptical

• irregular

• spiral

Why is new star formation rare in elliptical galaxies?

• they contain very little gas or dust

• all the gas and dust is trapped in exoplanets

• gas and dust repel each other and will not accumulate

• they contain too much gas and dust