Unit 34

Question 1

Elliptical galaxy

Answer 1

A galaxy with an elliptical shape and little dust or gas

Question 2

Spiral galaxy

Answer 2

A galaxy flattened into a disk shape with a pattern of spiral arms wound about a central nucleus. Spiral galaxies usually include dust, gas, and active regions of star formation.

Question 3

Dust lanes

Answer 3

The dark colored (brownish) squiggly line type structures visible in galaxies.

Question 4

Irregular galaxy

Answer 4

A non-symmetrical galaxy that does not have a well defined shape like either the spiral or elliptical galaxies. Irregular galaxies include dust, gas, and active star-forming regions

Question 5

Star cluster

Answer 5

A group of stars that formed from the same cloud of material and have been held together in a cluster by gravitational forces.

A small open cluster can consist of only a few dozen members while a large globular cluster can contain more than a million individual stars.

Question 6

What plays the biggest role in determining which type of galaxy forms?

Answer 6

Angular momentum

Question 7

Local group

Answer 7

A small group of about two dozen galaxies that is associated with our milky way (we’re in it)

Question 8

Galaxy cluster

Answer 8

A group of galaxies that is gravitationally bound together into a cluster, which vary greatly in size. A small cluster may have just a few members, while a large cluster may have several thousand.

Question 9

Supercluster

Answer 9

clusters of clusters of galaxies

Question 10

Void

Answer 10

The space between galaxy superclusters

Question 11

Cosmological red shift
(or just Red Shift)

Answer 11

The shifting of galaxy light to the red end of the spectrum caused by the expansion of the universe.
Doppler stuff. Think of the same affect of a police siren coming towards you, passing you, then moving away. The sound you hear at different points in this process will be different because of the wavelengths

Question 12

What is the Hubble Law?

Answer 12

The proportionality between the observed recessional velocity of a galaxy and the distance to that galaxy.

Question 13

Hubble constant

Answer 13

The constant of proportionality, H, in the Hubble Law. It gives the rate at which our Universe is expanding

Question 14

Cosmic microwave background

Answer 14

A uniform radiant field with an apparent temperature of 2.725 K that is observable in every direction.

Microwaves from the big bang. The universe’ temperature.

Question 15

What do the COBE and WMAP tell us?

Answer 15

That there are slight variations in the microwave temperature

Question 16

Dark matter

Answer 16

Unseen matter in galaxies and galaxy clusters that exerts gravity within them

Question 17

Dark energy

Answer 17

An energy associated with space that is causing the universal expansion to accelerate faster with time

Question 18

Cosmological constant

Answer 18

A constant introduced into the equations of general relativity by Albert Einstein in an attempt to cancel the predictions of the expanding nature of our universe.

Question 19

Where are newer stars and forming stars found in spiral galaxies?

Answer 19

In the arms