Astronomy

1.     In Ptolemy’s Earth-centered model for the solar system (not shown), Venus’s phase is never full as viewed from Earth because it always lies between Earth and the Sun. In reality, as Galileo first recognized, Venus is __________.

o   never full because the sunlit side of Venus never faces directly toward Earth

o   never full because Earth’s shadow falls on Venus at the time when it would otherwise be full

o   full whenever it lies directly between Earth and the Sun

o   full whenever it is on the opposite side of the Sun from Earth, although we cannot see the full Venus because it is close to the Sun in the sky

2.     Imagine that Venus is in its full phase today. If we could see it, at what time would the full Venus be highest in the sky?

o   Midnight

o   just before dawn

o   just after sunset

o   at noon

3.     When would a new Venus be highest in the sky?

o   Midnight

o   just before dawn

o   just after sunset

o   at noon

4.     When would you expect to see Venus high in the sky at midnight?

o   in its waxing gibbous phase

o   in its waning crescent phase

o   in its waxing crescent phase

o   in its full phase

o   never

5.     In Ptolemy’s Earth-centered model for the solar system (not shown), Venus always stays close to the Sun in the sky and, because it always stays between Earth and the Sun, its phases range only between new and crescent. The following statements are all true and were all observed by Galileo. Which one provides evidence that Venus orbits the Sun and not Earth?

o   We never see Venus at midnight.

o   We sometimes see a crescent Venus.

o   We sometimes see gibbous (nearly but not quite full) Venus.

o   We need a telescope to observe the phases of Venus.