Solar System Simulator · Sky · the Moon
Moon phase today
Tonight's Moon, worked out for your date and time zone.
Waxing Gibbous
95% lit · day 13 of 29.5
Next full moon: Sat, Sep 26
Next new moon: Sat, Oct 10
Coming up
| Phase | Date | Time |
|---|---|---|
| Full Moon | Sat, Sep 26 | 16:53 UTC |
| Last Quarter | Sat, Oct 3 | 13:28 UTC |
| New Moon | Sat, Oct 10 | 15:50 UTC |
| First Quarter | Sun, Oct 18 | 16:11 UTC |
| Full Moon | Mon, Oct 26 | 04:15 UTC |
| Last Quarter | Sun, Nov 1 | 20:29 UTC |
| New Moon | Mon, Nov 9 | 07:05 UTC |
| First Quarter | Tue, Nov 17 | 11:50 UTC |
Worked out on this page from the Moon's orbit; the times agree with published ones to within about a quarter of an hour.
The eight phases
Why the Moon has phases
Half of the Moon is always lit by the Sun. What changes is how much of that lit half faces us as the Moon goes round Earth: none at new moon, when it sits between us and the Sun, and all of it at full moon, when it's on the far side.
One lap round Earth takes 27.3 days, but new moon to new moon takes 29.5. While the Moon goes round, Earth moves on around the Sun, so the Moon needs about two more days to line up again. The simulator measures both as it runs.
What the simulator does
- Earth and the Moon seen from above, with sunlight coming from the Sun's real direction.
- The Moon starts at tonight's phase. Beside it is the same Moon as it looks from Earth.
- Two stopwatches time one lap round Earth and one full cycle of phases: about 27.3 and 29.5 days.
Questions people ask
Why does the Moon have phases?
The Sun always lights half of the Moon. As the Moon goes round Earth we see more or less of that lit half: none at new moon, all of it at full moon.
How long is a lunar cycle?
About 29.5 days from one new moon to the next. One lap round Earth is shorter, 27.3 days, because Earth moves on around the Sun in the meantime.
Does the Moon look the same from the southern hemisphere?
It shows the same phase, but upside down. This page draws it as seen from the northern hemisphere, lit on the right while it waxes; from the southern hemisphere a waxing Moon is lit on the left.
Keep going
Every number on this page comes from the simulator's own physics or the real mission record it is checked against. Where the simulation and reality differ, the page says so.