Astronomy Astronomy Galaxies and the Milky Way 2

Question 1

What will eventually happen when the Milky Way and Andromeda galaxies collide?

Accepted Answer

They will merge into a large elliptical galaxy

Answer

In approximately 4-5 billion years, the Milky Way and Andromeda will merge to form a large elliptical galaxy, sometimes called 'Milkomeda.'

Question 2

What is a galaxy cluster?

Accepted Answer

A gravitationally bound group of hundreds to thousands of galaxies

Answer

A galaxy cluster is a large, gravitationally bound structure containing hundreds to thousands of galaxies, hot gas, and dark matter.

Question 3

What is the Local Group of galaxies?

Accepted Answer

The gravitationally bound group containing the Milky Way and its neighbors

Answer

The Local Group is the galaxy group containing the Milky Way, Andromeda, Triangulum, and over 50 smaller galaxies, spanning about 10 million light-years.

Question 4

What causes the spiral arm structure seen in galaxies like the Milky Way?

Accepted Answer

Density waves that compress gas and trigger star formation

Answer

Spiral arms are caused by density waves rotating through the galactic disk, compressing gas and dust to trigger enhanced star formation that illuminates the arms.

Question 5

What is the difference between a Type I and Type II galaxy classification (de Vaucouleurs)?

Accepted Answer

This is not the correct classification system; Hubble tuning fork uses elliptical vs spiral vs irregular

Answer

The Hubble classification system (tuning fork diagram) classifies galaxies as elliptical (E0-E7), lenticular (S0), spiral (Sa-Sd), barred spiral (SBa-SBd), or irregular.

Astronomy Practice Test

Astronomy Practice Test

Astronomy Astronomy Galaxies and the Milky Way 2