Unit IX Test Review

Galaxies are colossal collections of stars, gas & dust held together by _____.

• space

• time

• gravity

• blackholes

Younger stars that orbit the galactic bulge are located in the

• Halo regions

• galactic disk

• galactic bulge

• density waves

The area where faint, old stars exists that surrounds the disk & bulge.

• Halo region

• galactic bulge

• galactic disk

• spiral density region

The Milky Way measures ____ light years in length.

• 26,000

• 1 million

• 1,000

• 100 thousand

The Milky Way only measures about ____ light years in thickness.

• 26,000

• 100,000

• 1,000

• 1 million

Figuring out what the Milky Way looks like is difficult because

• we live outside of it.

• it is impossible to send a space probe that far.

• we live inside of it

• it is full of dark matter

Our Sun and solar system lies within the ____ arm of the Milky Way galaxy.

• Cygnus

• Perseus

• Sagittarius

• Orion

Variable stars are stars that fluctuate in

• size.

• magnetic field strength.

• temperature

• brightness.

Astronomers use the period-luminosity of variable stars to help

• determine the age of our galaxy

• determine galactic distances and sizes.

• determine the age of our universe.

• discover supernovae.

Variable stars include short period RR Lyrae & longer period Cepheids.

• True

• False