Moon to the Eclipse:
7/16/17 Quarter Moon
A weekly moonwatch as the eclipse approaches
by Eileen Campbell • July 16, 2017
Quarter moon, waning
(Photo by NASA)
Tonight is a quarter moon. Which is confusing, because you see half of the moon lighted up. But the name refers to the moon’s journey: it is now a quarter of the way through its monthly trip around Earth. In its current position, the moon shows us half of its lighted side and half of its shadowed side.
The moon is now waning, or growing steadily smaller from its full phase last week. Every time you see the moon for the next week, it will appear smaller and thinner, until it disappears entirely.
This is a good time in the moon’s orbit to look for it during the daytime. It doesn’t rise until after midnight, but it will still be up in the morning sky, visible to the south. (You can look up moonrise and set times for your location online.) The moon is up in the day as often as it is in the night, but it’s easier to see when it’s closer to full. As it becomes a thin crescent, it will be increasingly difficult to make out against the bright daytime sky.
(next post in our Moon to the Eclipse series)
The moon orbits the Earth about once a month. As it circles our planet, we see different amounts of the lighted and dark sides of the moon. The blue boxes mark tonight’s moon.
(Orbit illustration by Karl Tate, SPACE.com, from NASA. Moon phase photos by Fred Espenak.)