19. An observer at 40* North Latitude took a time exposure
photograph from 10 p.m. to midnight of the stars over the northern horizon.
Which explanation below best describes why this pattern occurs
in the stars?
a. The earth revolves around the
sun.
b. The earth rotates on its axis.
c. The stars revolve around the
earth.
d. Earth's gravity attracts the
stars.
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Slichter