Lunar Phases Interactive (124.0K)
Everyone is aware that the Moon changes its appearance from day to day. This Interactive will show you why, and allow you to understand how the Moon’s phases are linked to where and when each phase appears in the sky. If it’s sunset, and the Moon is directly overhead, what phase must it be? Is it possible to see the full Moon during the day? What exactly does a “waxing gibbous” Moon look like? Playing with this Interactive will give you a real understanding of how the interplay between Moon, Earth and Sun creates what we see.
These phases can be matched to the appearance and rising a setting times for the Moon in this cycle, as we shall explore with this interactive and this question.
As the moon takes about 30 days to circle the sky, each day it moves about 12 degrees on average. Let's see how this relates to civil time keeping.
The phase, or synodic month, is 29.5 earth days long. Let's see how this relates to one of the rarer calendar cycles, since our modern months are only loosely based on the original phase cycles.
The cycle of lunar phases gave us our month, and a predictable set of alignments that still today set the Muslim, Chinese, and Jewish calendars, as well as the date of Easter Sunday for Christians. Of these, only the Muslim one makes no adjustments for the solar year, however.