Today the Moon will be in a First Quarter phase. This phase occurs roughly 7 days after the New Moon when the moon is one quarter of the way through its orbit around the earth. Exactly half the moon will be illuminated and half dark. On the day of the First Quarter phase the moon is high overhead at sunset and is visible until mid-night when it sets in the west. The First Quarter phase is a one-day event and in the following days enters a Waxing Gibbous phase becoming more illuminated each day until the Full Moon.
Visit the May 2021 Moon Phases Calendar to see all the daily moon phase for this month.
First Quarter Phase
The First Quarter on May 19 has an illumination of 47%. This is the percentage of the Moon illuminated by the Sun. The illumination is constantly changing and can vary up to 10% a day. On May 19 the Moon is 7.09 days old. This refers to how many days it has been since the last New Moon. It takes 29.53 days for the Moon to orbit the Earth and go through the lunar cycle of all 8 Moon phases.
You can use this link to go forward or backward in time for Moon phase information. If you are curious you can even find out what phase the Moon was in when you or anyone else, you know was on the date the person was born.