__________is the stage in the early history of the Universe when ultraviolet photons from the first stars ionized the gas filling space
A) Unionization
B) Replication
C) Recombination
D) Reionization
D
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The purpose of using epicycles and deferents to explain the motion of the planets in the night sky was to account for
a. prograde motion. b. Mercury's and Venus's limited angular distance from the Sun. c. retrograde motion. d. non-uniform speed of the planets in their orbits. e. precession of the equinoxes.
Which exoplanet detection method requires us to be in the same plane as the exoplanetary system?
A. Direct imaging B. Transit method C. Radial-velocity method D. Gravitational lensing E. None of these choices are correct.
Relate Kepler's Second Law to the speeds of the planets
What will be an ideal response?
If the Sun were to magically and instantaneously be replaced by a 1 solar mass black hole, what would happen to the Earth's orbit?
A) It would be unchanged. B) It would be much smaller, but its shape would be unchanged. C) It would be at the same distance from the Sun, but would be much more eccentric. D) It would be much larger, but its shape would be unchanged. E) The Earth would be pulled into the black hole and destroyed.