A total eclipse of the sun occurs during what we call "new moon." New moon is when the moon in its orbit moves more or less between the earth and the sun. The night side of the moon faces us, and the moon is invisible. When the moon, sun and earth form a straight line, there is a total solar eclipse somewhere on the globe. An eclipse does not occur every new moon because the moon's orbit is inclined to the ecliptic by 5 degrees. Generally, the moon passes above or below the sun. During a total solar eclipse, the moon covers the sun, plunging the earth into darkness up to 7 1/2 minutes. Eclipses vary in duration depending on the moon's distance from us at the time. It is a perfect fit, the only two discs in our sky, one on top of the other like a quarter placed on top of another quarter.

The sun's diameter is 400 times larger than the moon's. The sun is also 400 times farther away. This amazing coincidence makes solar eclipses possible. The sun is about 93 million miles from us. The moon is about 240 thousand miles. Divide 240,000 into 93,000,000, and you get 388. Close enough! The moon was created when a planet-size object collided with the early earth, sending debris into orbit. This debris coalesced over time to form the moon. The moon was once much closer than it is now. It is slowly drifting away, and there will come a time in the remote future when the full moon will not be large enough to cover the sun. The age of total solar eclipses will have ended.

The Great American Eclipse of August 21, 2017, will begin in the Pacific Ocean. The moon's shadow will first touch land in Oregon. It will cut a diagonal path across the United States. The ideal place for me to see it is in Lebanon, Tennessee, 30 miles east of Nashville. I lived in Lebanon in the 1970s and 80s and know the town. I had a house there. There will be an estimated 2 minutes, 35 seconds of totality. From Tennessee, the moon's shadow will cross Charleston, South Carolina, and move into the Atlantic Ocean, leaving the earth close to Africa.

The partial phase will begin in Lebanon just before noon, Central Time. Totality will occur about 1:30pm. The eclipse will end about 3pm. Eclipse glasses are needed for the partial phases. Only during totality can the eclipse be viewed without glasses. The sun's corona is visible at this time. The corona is the sun's outer atmosphere. It is made of plasma, the 4th state of matter. Hot! Hot! Hot! The outer corona is delicate, wispy and pearly white. The moon appears as a black disc covering the sun with the corona streaming from it. it has been called "the eye of God!" We see eruptions of gas called prominences coming from the sun's surface. We see stars and planets, possibly Mercury. We look around. We see the shimmering shadow bands. Nothing is familiar! It is as if the light of the partial phases is coming from a different star. Animals go crazy! Dogs bark. Birds return to their nests. People scream! They feel a connection with the universe and with their primitive ancestors!

Right before and right after totality, we see Baily's Beads and the Diamond Rings. Baily's Beads are the sun's rays passing through mountains and valleys on the moon. They were named after Francis Baily. The Diamond Ring effects are created by the last bead before totality and the first Bead after totality. From beginning to end, this eclipse will last 3 hours.

All solar eclipses are different. The path of this one is 67 miles wide. It is like a ribbon stretching across the United States. We want to be as close to the middle of that ribbon as possible. Be prepared to drive west or east to avoid clouds. The moon's shadow will approach from the west and disappear in the east.

Jim Colyer
July, 2017