An extrasolar planet is
a. a planet that orbits our sun that we have not yet discovered.
b. one not needed for the formation of our solar system which is kept in a special area just in case.
c. a planet found orbiting around a star other than the sun.
d. another name for an asteroid.
e. a planet extra close to our sun.
Question 2Why is the cosmic microwave background (CMB) so cold if the early universe was so hot?
a. Enough time has passed for matter in the universe to release enough heat to cool down.
b. The CMB constantly interacts with atoms, which effectively cool down the photons.
c. The expansion of the universe has redshifted those photons to an effectively cooler temperature.
d. Misleading; The Big Bang was initially hot but the CMB was released from cold material much later on.
Question 3The oldest rocks found on Earth are about ____ years old.
a. 14 billion
b. 10.5 billion
c. 7.0 billion
d. 3.9 billion
Question 4Where did the cosmic microwave background (CMB) come from?
a. Photons emitted from the first stars
b. Photons released from hydrogen in our galaxy
c. Light scattered by dust in our Solar System
d. Photons released when electrons and nuclei combined for the first time.
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