Most cosmologists favor the Big Bang theory over other cosmological theories because of
a. a 3-to-1 ratio of hydrogen to helium in stars and interstellar matter.
b. cosmological redshifts.
c. the cosmic microwave background.
d. all of the above.
d
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____ galaxies have a great many short spiral segments branching from the spiral arms
a. Grand design b. Super spiral c. Cepheid d. RR Lyra e. Flocculent
In principle, if we could see all the way to the cosmological horizon we could see the Big Bang taking place. However, our view is blocked for times prior to about 380,000 years after the Big Bang. Why?
A) Before that time, the universe was too crowded with stars. B) Before that time, the gas in the universe was dense and ionized and therefore did not allow light to travel freely. C) Before that time, the universe was dark so there was no light to illuminate anything. D) 380,000 years after the Big Bang marks the time when stars were first born, and thus began to shine the light by which we can see the universe.
Which statement about the rotations of the Moon and Mercury is FALSE?
A) Our Moon is in a 1:1 synch with the Earth, keeping the same side toward us. B) Mercury is in the 3:2 synch with the Sun, with the same side Sunward at perihelion. C) Like our Moon, Mercury does not rotate at all, keeping the same side facing the Sun. D) On Mercury, three days exactly equal two years. E) On the Moon, each "day" lasts about 15 Earth days of constant sunlight.
Saturn's cloud surface appears more uniform than Jupiter's because
A) there is a thick outer cloud covering of water ice overlying the colorful ices. B) due to Saturn's lower gravity, the colorful cloud layers escaped. C) it is composed of completely different gases than Jupiter's. D) the cloud layers are thicker, allowing fewer holes to see the colorful layers. E) due to Saturn's greater distance from the Sun, the colorful cloud layers are just not visible.