Expert: Philip Stahl - 4/30/2009

Question
Is there a time of year or month when the moon and sun follow close to the same path in the sky? Also is there a best time to see the moon? Currently the moon seems to be setting only a few hours after the sun does.

Answer
Hello,

I am aware of no specific time of year where the Moon and Sun follow the same path in the sky, other than near eclipses (e.g. solar, when the Moon and Sun are at the same point in the ecliptic). Generally, this will not be so because the Moon's orbit is inclined at a slight angle (~ 5 deg) to the ecliptic.

As to the best time to observe the Moon, that depends on what one wants to see. For example, some observers want to view the whole, fully lit face - so the full Moon is the best time to observe for them. My wife prefers to see the shadows of lunar mountains so the terminator will need to be visible - so any time just before or after first quarter (or 3rd) is the ideal time for her.

Re: your last statement, correct, since the New Moon just occurred last Friday (24th), so the Moon now "follows" the Sun in the sky. In another week or so it will be setting nearly 12 hours after the Sun - and so be in "opposition" and we will have full Moon.