First quarter moon意思

"First quarter moon" is a lunar phase that occurs about seven days after the new moon. At this stage, the moon has moved in its orbit around Earth to a position where it is about 90 degrees from the sun as seen from Earth. This means that the moon is now half-illuminated by the sun's light, with the illuminated half visible from Earth.

The first quarter moon rises around noon and sets around midnight, so it is visible in the afternoon and evening skies. It appears as a half-moon shape in the sky, with the right side illuminated if you are in the Northern Hemisphere, and the left side illuminated if you are in the Southern Hemisphere.

This phase is called the "first quarter" because it is the first of the two quarter phases of the moon (the other being the third quarter), and it marks the halfway point between the new moon and the full moon. After the first quarter, the moon continues to move around Earth, and the illuminated portion of the moon grows larger until it reaches the full moon phase, which occurs about two weeks after the new moon.