How did Edwin Hubble measure the distance to the Andromeda Galaxy?
A) He measured its parallax.
B) He applied the period-luminosity relation to Cepheid variables.
C) He deduced it from its redshift.
D) He used white dwarf supernovae.
Question 2
What use are 21 cm radio waves to Galactic astronomers?
A) They cut through the dusty cocoons to let us watch star birth.
B) We can reflect them off the core of the Galaxy.
C) Their Doppler shifts let us map the motions and locations of gas in the spiral arms.
D) They bounce off stars like our Sun to let us precisely measure their distances.
E) They pick up the cool, dark matter much better than can optical telescopes.
True-color view of Mars seen through NASA's Hubble Space Telescope in 1999
A Starburst Galaxy
The secular trend in growth as measured in Swedish (a) girls and (b) boys between 1883 and 1968.
Performing a Spirometry Test to Measure Forced Vital Capacity
Sample Items from the Brief Multidimensional Measure of Religiousness/Spirituality (BMMRS)
Ways to Measure Percentage of Body Fat