Look up at the sky tonight or any night in the next few days. The brightest thing in the sky is the Moon. Our Moon will play a key role in the coming total solar eclipse. Between now and the 21st of August, the Moon will move from its current position, slowly closing in on the Sun. On August 21 the Moon will slide between Earth and Sun, casting its shadow on Earth. You can watch this drama starting right now. If you look at the Moon in the next few nights, you will notice that shortly after the Sun disappears below the western horizon you can turn to the eastern horizon to see the Moon rising higher into the sky.
Continue to watch every night, you will notice that the Moon is closer to the horizon each night at sunset. Next week if you look for the Moon it won't be in the sky until after sunset. At the same time you will notice that the Moon changes in appearance, becoming fully lighted, full Moon. A few nights later the Moon will begin to darken along one side and you will have to stay up later to see it in the sky. All of this can be quite mysterious until you think about what is happening in three dimensions.
At this point the show becomes much more exciting. You will be able to see the Moon in the morning sky before sunrise. Watch carefully each day as the Moon moves closer to where the sunrise is occurring. In the days just before the total solar eclipse, a thin crescent Moon will be poised in the eastern sky above the sunrise point. You will have to look very carefully to find it in the eastern sky on August 19. Few people will be able to find the Moon on the morning of August 20 but if you have been watching you will have a real good idea where it is hiding in the glare of the Sun. On August 21 the invisible Moon will slowly reveal itself as it slides between Sun and Earth. Of course we won't be seeing the familiar Moon we are used to seeing. During the eclipse we will see it's silhouette as it moves between us and the Sun. If you are fortunate enough to be within the ribbon of totality, the Moon will slide across the face of the Sun and for just a few precious seconds the Moon will fit exactly over the Sun. Then just as fast as it moved in front of the Sun it will retreat, slowly exposing the full face of the Sun. Once more, the Moon will become invisible. By the evening of August 23 or 24 you will once again see the Moon in the night sky.
When it makes it's reappearance, be sure to give it the applause it deserves. That wonderful total solar eclipse you saw was brought to you by the greatest supporting actor of all time, our Moon.
If you watch each night and morning until the eclipse you can also challenge yourself to think in three dimensions about what you are seeing. See if you can keep track of where the three actors in this play are each night. Earth, Sun, Moon in a dance of the centuries. The show never ends. Follow it every night, just as your ancestors did.