Galaxies

Galaxies

Quiz on Galaxies pages 1-7

Measuring Distance

• Megaparsecs: used by astronomers to measure great distance (equals 3, 260, 000 light-years)

• Most distant galaxies that are still visible using large telescopes and photography are 3,000 megaparsecs away from earth.

Clusters

• Definition: groups of (a differing number of) galaxies, ranging from a few to the thousands.

• Rich clusters: clusters with over a thousand galaxies that are more concentrated toward their centers, and often have a giant elliptical galaxy at their centers. Example: virgo cluster.

• Poor clusters: clusters with fewer than a thousang galaxies, many with irregular shapes/forming small groups called subclusters. Example: The Local Group.

The Local Group

• A group of approx. 20 galaxies all in the same area.

• Two main members: Milky Way and Andromeda (next most important: Triangulum).

Fill in the Blanks

What is used by astronomers to measure great distance? (hint: it equals 3, 260, 000 light-years)

Fill in the Blanks

What is the name of the cluster where our galaxy belongs?

Multiple Choice

Our galaxy is within a _____ cluster.

• rich

• poor

Fill in the Blanks

Approximately how many galaxies are within the local group?

Radio Galaxies

• Emit large amounts of radio waves

• Some emit over ten million times as much radio-wave energy as normal galaxies.

Quasars

• Extremely bright, distant galaxies that look like stars and change in brightness

• Far away: from one bliion to fifteen billion light-years from earth

• Can be 1,000 times brighter than a normal galaxy

Fill in the Blanks

These galaxies can be 1,000 times brighter than a normal galaxy.

Fill in the Blanks

What kind of galaxies emit large amounts of radio waves?

Open Ended

Bonus Question: would you ever want to be an astronaut?