What the moon is doing over the next few days
Each card above is worked out for midday on that date: the shape of the lit portion, the percentage illuminated, and the sign the moon is passing through. Scroll the sidebar for tonight's rise and set times for your city.
Waxing or waning — telling them apart
In the northern hemisphere the lit edge tells you which way it is going. Light on the right means waxing, growing towards full. Light on the left means waning, shrinking towards new. South of the equator it is reversed, which is the sort of detail that catches people out on holiday.
The old mnemonic is that a waxing moon makes the shape of a D and a waning moon makes a C. It works, in the north.
Why the percentage moves so unevenly
Illumination changes fastest around the quarters and slowest around new and full. That is why a moon can look full for two or three nights running while the number barely shifts, and then appear to change noticeably from one evening to the next a week later. It is only exactly full for an instant — those instants are listed here.
Rising later every night
The moon rises around fifty minutes later each day, because it has moved along its orbit while the earth turned. That is why a full moon rises about when the sun sets and a new moon is up in the daytime where nobody notices it. It is also why some nights have no moonrise at all in the calendar day.