Health Warning! This is not necessarily everything you need to know from this lecture! I maintain exactly what you need to
know through the first few lectures as some people add the course late. But these questions are to help with just the most difficult concepts in
some lectures. If you want to discuss any of these concepts more, come see me during office hours.
The phases of the Moon
The University of Nebraska-Lincoln have a nice applet on this.
Draw a diagram that shows the Sun on one side of the page and the Earth in the center. Draw the Moon in four positions around the Earth, corresponding to New Moon, First Quarter, Full Moon and Third Quarter. Mark the times of day as observed from Earth. To do this, ask yourself, what time is it when the Sun is "overhead"*? What time is it when the Sun is on the opposite side of the Earth to the observer?
About what time of day is a New Moon overhead? A Full Moon? First Quarter? Third Quarter?
Draw a Waxing Crescent, Waxing Gibbous, Waning Crescent, Waning Gibbous on your diagram. About when is the Moon overhead in the sky during those phases?
About what time of day does a Full Moon rise? About what time of day does a Full Moon set? What about a New Moon? First Quarter? Third Quarter?
If it is daytime and a First Quarter Moon is on the horizon, about what time of day is it?
(As viewed from Earth) what side (left or right) of the Moon is illuminated at First Quarter? Third Quarter? Waxing Gibbous? Waning Crescent?
Can you ever see a Third Quarter Moon above the horizon at 10am? What about a First Quarter Moon? A Full Moon? A New Moon?
What is the phase of the Moon during a lunar eclipse? A solar eclipse?
What is a penumbral eclipse? A partial eclipse? An annular eclipse? Are annular eclipses solar or lunar?
Why do annular eclipses happen?
What color is the Moon during a total lunar eclipse? Why?
If lunar and solar eclipses happened on every orbit of the Moon around the Earth, how often would we get each type of eclipse?
Why don't we get eclipses as often as this? What is the ecliptic?
The synodic month (between phases) is about 29.5 days long. The sidereal month (one full orbit of the Moon around the Earth) is about 27.3 days long. Why is there a difference?
HARDER...you'd never need to know this. One orbit of the Moon around the Earth (one sidereal month) takes 27.3 days. If the Earth goes a full orbit of 360° around the Sun in 1 year (365 days) how many degrees around the Sun has the Earth moved in one sidereal month (answer is about 27°)? If the Moon takes 27.3 days to move 360° in its orbit, how long does it take to move 27°? Why is the synodic month about 2 days longer than the sidereal month?
HARDER...you'd never need to know this. One orbit of the Moon around the Earth (one sidereal month) takes 27.3 days. If the Moon appears to move 360° around the sky in one sidereal month, how many degrees does the Moon appear to move in the sky each day (answer is about 13.2°)? If the Earth turns through 360° in one day, how long does it take the Earth to turn 13.2°? Why does the Moon rise about 52 minutes later each day?
*Note that the Sun and Moon don't really get directly overhead everywhere on Earth (as in "right at zenith"). They get directly overhead if you live in the tropics at some point in the year. In other places they just get to their "highest point in the sky". This highest-point-in-the-sky-but-not-directly-overhead is referred to as "crossing the meridian". The meridian is the line that runs North/South through zenith.