Which of the following would not be considered evidence for dark matter in clusters of galaxies?
A) the total amount of stars
B) the temperature of the intergalactic gas
C) the velocities and radii of galaxy orbits around the center of mass in the cluster
D) the curvature of gravitationally-lensed galaxies
Question 2
The choices below describe four hypothetical planets. Which one would you expect to have the most features of erosion? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.)
A) Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours.
B) Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days.
C) Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months.
D) Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours.
Barred Spiral Galaxies
Galaxies with Rings
Mapping Dark Matter
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