A first quarter moon shows half of its lighted hemisphere – half of its day side – to Earth.
The moon reaches first quarter on October 9, 2016 at 0433 UTC; translate to your timezone. The full moon will come on the nights of October 15-16. It will be the Hunter’s Moon and also a supermoon.
We call this moon a quarter and not a half because it is one quarter of the way around in its orbit of Earth, as measured from one new moon to the next.
Also, although the moon appears half-lit to us, it’s good to recall that the illuminated portion of a first quarter moon truly is just a quarter. On the night of first quarter moon, we see half the moon’s day side, or a true quarter of the moon. Another lighted quarter of the moon shines just as brightly in the direction opposite Earth!
And what about the term half moon? That’s a beloved term, but not an official one.
A first quarter moon rises at noon and is highest in the sky at sunset. It sets around midnight. First quarter moon comes a week after new moon. Now, as seen from above, the moon in its orbit around Earth is at right angles to a line between the Earth and sun.
High security for the European Space Centre