The Moon makes no light of its own: we see the half lit by the Sun, from an angle that changes as the Moon circles the Earth. At new moon it lies roughly between the Earth and the Sun and shows us its dark side; a week later, at first quarter, we see half of its disc lit; at full moon it is opposite the Sun and fully lit; then it wanes back. The whole cycle takes about 29.5 days. The phase is the same for everyone on Earth at the same moment, but in the Southern Hemisphere the lit side appears flipped.
What is the Moon’s phase today?
Computing…
Questions and answers
Why does the Moon have phases?
Half of the Moon is always lit by the Sun; as it orbits the Earth, we see more or less of that lit half.
Is the phase caused by the Earth’s shadow?
No. The Earth’s shadow only falls on the Moon during a lunar eclipse, at some full moons.
Where the numbers come from
Values refresh every second in your browser; the published data are checked every 10 minutes and updated several times a day.