The Phases of the Moon
The Moon revolves around Earth every 27.3 days. The Moon also takes 27.3 days to rotate. As a result, the same side of the Moon is always facing us. Like all bodies in the solar system, one side of the Moon is always illuminated by the Sun. However, this bright sight does not always face Earth. As a result, we see different amounts of the lit side at different times. Since the Moon is spherical, the illuminated portion is curved. A simple way to remember the phases of the Moon is to think of the lit side increasing from right to left across the surface of the Moon during the waxing phases and the dark side increasing from right to left during the waning phases.
Phases of the Moon
Instructions
How to read diagram: The diagram lists the phases of the Moon. However: Where does the diagram start? What’s the Moon’s first phase? Which way do we read the diagram?
Well, first, start at New Moon, then, read the diagram going clockwise starting with the “lower part.” So, the next phase of the Moon would be waxing crescent, then first quarter, and so forth.
Note: Last Quarter is also sometimes referred to as Third Quarter.
Review
If you would like to see the lunar cycle in action, here is a video: Animation of the Moon
If you need review, here is a video to help you do that: Lunar Cycle Video Review (Note that the video talks a little about eclipses. I will talk about eclipses in my next blog post 😉 )
Check out this interactive lab!
Check Your Understanding
Check your understanding with this Lunar Cycle Game
Clinton's Astronomy Blog 