EXERCISE 17

Are the following Moon shapes and orientations possible?  If so, give one
example of a Moon phase and time of day or night when it can happen.  If not,
explain why not.
   (a) Crescent moon near the eastern horizon, with the concave edge facing up.
   (b) Crescent moon near the western horizon, with the concave edge facing up.
   (c) Crescent moon near the eastern horizon, with the concave edge facing down.
   (d) Crescent moon near the western horizon, with the concave edge facing down.
   (e) Crescent moon transiting, with the concave edge facing east.
   (f) Crescent moon transiting, with the concave edge facing west.