The first attempt to map the Galaxy via star counts was done by
A) William Herschel in the late eighteenth century.
B) Edwin Hubble with the new 100" Mt. Wilson telescope in the 1930s.
C) Harlow Shapley with the RR Lyrae variables in 1920.
D) Edward Barnard with long exposure photos about 1900.
E) Galileo in 1612.
A
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Characteristics of Waves: A fisherman fishing from a pier observes that the float on his line bobs up and down, taking 2.4 s to move from its highest point to its lowest point. He also estimates that the distance between adjacent wave crests is 48 m. What is the speed of the waves going past the pier?
A. 1.0 m/s B. 20 m/s C. 10 m/s D. 5.0 m/s E. 120 m/s
Why is the nightside of Mercury so much colder (relatively speaking) than the dayside?
A. Mercury is in synchronous rotation, so the far side of Mercury never sees the Sun. B. Mercury's lack of an atmosphere keeps the planet from retaining its surface heat. C. Mercury's small size lets it cool quickly. D. Mercury's magnetic field acts like a blanket on the planet's dayside.
What would happen to Earth's temperature if you painted the entire surface of the Earth black?
A) Its average temperature would go up. B) Its average temperature would go down. C) Its temperature would not change.
About how hot was the Big Bang when matter and energy "decoupled"?
A) 900 million K B) 15 million K C) 3,000 K D) 300 K E) 2.73 K