Moon to the Eclipse:
7/8/17 Full Moon
A weekly moonwatch as the eclipse approaches
by Eileen Campbell • July 8, 2017
The full moon
Photo by NASA/Bill Ingalls
Tonight is the full moon, and we’re now only a moon cycle and a half before the total solar eclipse. It’s a good time to begin watching the moon. If you follow its cycle through the next month, you’ll get a sense of the moon’s motion relative to Earth and the Sun. Then you’ll be ready to watch as it crosses the stage for its big scene eclipsing the Sun.
Some basics to help your observations: The moon, just like Earth, is lit by the Sun. It has a lighted and a dark side, just like our planet’s day and night sides. We can see that from Earth, and that’s what makes the moon’s phases: full, quarter, crescent, new. At a full moon, you see the fully lighted side of the moon. At a quarter moon, you see some of both the lighted and the dark sides. (Although all you really see is the lighted side, since the dark side is in shadow.) At a crescent moon, only a sliver of the lighted side is visible. At a new moon, it seems as though the moon has disappeared, because its dark side faces Earth. Because it’s not lit, we can’t see it. An eclipse happens at the new moon, when the moon is between Earth and the Sun.
Go outside tonight and look up at the glorious, fully lighted moon. Then keep watching, night after night. This blog will watch with you and talk through what we see.
(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.