Dark matter is detectable in the coronae of ____.
a. elliptical galaxies only
b. spiral galaxies only
c. irregular galaxies only
d. spiral and elliptical galaxies only
e. all galaxies
Question 2
What modern-day instrument do astronomers use to record images from telescopes?
a. photometer
b. grating device
c. spectrograph
d. photographic plate
e. charge coupled device