[mariaguimaraes (OP)]

Maria Guimarães  asked the Naked Scientists:
   
Hi Chris,
 
In the Southern hemisphere, where I live, the crescent moon appears as a C in the sky. On the same day, you will see the opposite: a D without the straight part. I keep trying to represent sun, earth and moon alignments but can't figure it out. And how is it on the Equator? U and inverted U? And what about the poles?
 
Thanks, Maria

What do you think?

[mariaguimaraes (OP)]

wow, this really IS complicated! i'll spend many nights with this in mind trying to really understand it.
Thanks!

[mariaguimaraes (OP)]

just to make sure I got it: the moon follows the equator, approximately?

[wolfekeeper]

No, it's not in the equatorial plane, it's nearly in the plane of Earths orbit (the plane of the ecliptic), don't forget that the plane of the equator is tilted at 23 degrees with respect to the orbit, actually it's about 5 degrees off the ecliptic, which puts it between 18 and 28 degrees from the equatorial plane.

(See http://en.wikipedia.org/wiki/Moon#Orbit_and_relationship_to_Earth)