Astro test 5 UPDATED ACTUAL Exam
Questions and CORRECT Answers
What evidence says we live in a disk galaxy? - CORRECT ANSWER - When we look
perpendicular we see less stars then looking parallel
Why is it difficult to map out the galaxy from earths vantage point? - CORRECT
ANSWER - Because of where we are located, its hard to define ambiguous objects in
some directions, while in others objects are completely blocked from our view
in what region of the galaxy are globular clusters found - CORRECT ANSWER - halos
How are cepheid variables used to determine distance? - CORRECT ANSWER - Infer its
luminosity, then infer its distance via: AP = L/D
Roughly how far out in space can we use Cepheids to measure distance? - CORRECT
ANSWER - 25Mpc
What two important discoveries were made using RR Lyrae variables? - CORRECT
ANSWER - - Most globular clusters stay far away from the sun
- By measuring the direction and distance of each cluster they created a 3D map of cluster
distribution
What use is radio astronomy in the study of galactic structure? - CORRECT ANSWER -
most knowledge on the structure of the galactic disk is based on radio, mainly 21 cm emission
Contrast the motions of disk and halo stars - CORRECT ANSWER - Disk motions move
on a plane in the same direction, halo stars are random
How do we know that the milky way has spiral arms? - CORRECT ANSWER -
measurement of the motion and position of gas clouds
, Why are galactic arms thought to be locations of recent/ongoing star formation? - CORRECT
ANSWER - As gas clouds pas through the arms, they trigger star formation via increased
density
What do red stars in the galactic halo tell us about the History of the milky way? - CORRECT
ANSWER - That the halo is really old, and the disk is new
What evidence is there for dark matter in the galaxy? - CORRECT ANSWER -
gravitational pull alone
Why can't optical astronomers easily study the center of our Galaxy? - CORRECT
ANSWER - too many stars, it would be too bright to individually look at single stars
In the milky way our sun is located where. - CORRECT ANSWER - halfway out from the
center
Where are the first stars that formed in the milky way - CORRECT ANSWER - in random
orbis around the halo
Most of the mass in the milky way consists of... - CORRECT ANSWER - dark matter
What distinguishes one spiral galaxy to another? - CORRECT ANSWER - A spiral galaxy
(S) is givin an a, b, or c according to size. Sa is the biggest with tighter arms.
Describe some similarities and differences between elliptical galaxies and the halo of our own
Galaxy. - CORRECT ANSWER - Elliptical galaxies have no spiral arms and no obvious
galactic disk
Describe the four rungs in the distance measurement ladder - CORRECT ANSWER --
radar ranging
Questions and CORRECT Answers
What evidence says we live in a disk galaxy? - CORRECT ANSWER - When we look
perpendicular we see less stars then looking parallel
Why is it difficult to map out the galaxy from earths vantage point? - CORRECT
ANSWER - Because of where we are located, its hard to define ambiguous objects in
some directions, while in others objects are completely blocked from our view
in what region of the galaxy are globular clusters found - CORRECT ANSWER - halos
How are cepheid variables used to determine distance? - CORRECT ANSWER - Infer its
luminosity, then infer its distance via: AP = L/D
Roughly how far out in space can we use Cepheids to measure distance? - CORRECT
ANSWER - 25Mpc
What two important discoveries were made using RR Lyrae variables? - CORRECT
ANSWER - - Most globular clusters stay far away from the sun
- By measuring the direction and distance of each cluster they created a 3D map of cluster
distribution
What use is radio astronomy in the study of galactic structure? - CORRECT ANSWER -
most knowledge on the structure of the galactic disk is based on radio, mainly 21 cm emission
Contrast the motions of disk and halo stars - CORRECT ANSWER - Disk motions move
on a plane in the same direction, halo stars are random
How do we know that the milky way has spiral arms? - CORRECT ANSWER -
measurement of the motion and position of gas clouds
, Why are galactic arms thought to be locations of recent/ongoing star formation? - CORRECT
ANSWER - As gas clouds pas through the arms, they trigger star formation via increased
density
What do red stars in the galactic halo tell us about the History of the milky way? - CORRECT
ANSWER - That the halo is really old, and the disk is new
What evidence is there for dark matter in the galaxy? - CORRECT ANSWER -
gravitational pull alone
Why can't optical astronomers easily study the center of our Galaxy? - CORRECT
ANSWER - too many stars, it would be too bright to individually look at single stars
In the milky way our sun is located where. - CORRECT ANSWER - halfway out from the
center
Where are the first stars that formed in the milky way - CORRECT ANSWER - in random
orbis around the halo
Most of the mass in the milky way consists of... - CORRECT ANSWER - dark matter
What distinguishes one spiral galaxy to another? - CORRECT ANSWER - A spiral galaxy
(S) is givin an a, b, or c according to size. Sa is the biggest with tighter arms.
Describe some similarities and differences between elliptical galaxies and the halo of our own
Galaxy. - CORRECT ANSWER - Elliptical galaxies have no spiral arms and no obvious
galactic disk
Describe the four rungs in the distance measurement ladder - CORRECT ANSWER --
radar ranging
