On the city forecast pages, we list the current and future moon phases. But why does the moon have different phases?
It all has to do with the sun. Because the moon orbits Earth, it causes the portion we see illuminated to change, the different phases we see is because portions of the Earth blocks out parts of the moon.
The Moon takes 27.3 days to orbit Earth, but the lunar phase cycle, from new Moon to new Moon, is 29.5 days.