1. Great American Eclipse

2. Chinese astrologers wrote of an eclipse occurring over 4000 years ago.
Historians and astronomers believe that this was an eclipse that happened on 22 October 2134 B.C.
Two astrologers at the time, Hsi and Ho, had apparently failed to predict this eclipse, and so were beheaded.
Eclipses had mystical origins for thousands of years. The Chinese believed the sun was being eaten by dragons. They could predict eclipses through careful observations of the sun and moon. Failure to predict an eclipse was often met with death.

3. What is a Solar Eclipse?

4. BASIC ECLIPSE GEOMETRY
The moon orbits the Earth once every 29.5 days. This is called a synodic lunar month and is defined as the time between new moon and the next new moon. This is slightly longer than a “sidereal” lunar month (27.3 days) which is the time it takes the moon to go 360 degrees around the Earth, because the Earth will have advanced in its orbit by about 27 degrees . To get back to a new moon, the moon then has to travel a little further each sidereal month to get back into a straight line with the sun and Earth. Eclipses do not, however, occur every 29.5 days because the moon’s orbit around the Earth is tilted with respect to the Earrth’s orbit by about 5 degrees, enough to make the moon’s shadow miss too high or too low most of the time. Eclipses can occur only when the sun, moon, and Earth line up along the line of nodes which is the intersection of the Earth’s orbital plane with the moon’s orbital plane.

5. This graphic illustrates how the shadow of the moon falls on the Earth during a total solar eclipse. Notice how small and narrow the path of totality is. The darker central shadow is called the umbral shadow. Viewers inside this small shadow area will see a total eclipse. The lighter shadow is called the penumbral shadow. Observers within the penumbral shadow will see a partial eclipse. The umbral shadow advances across the face of the Earth at a little over 1000 miles per hour. This motion is due largely to the Earth’s rotation on its axis.

6. Why is a solar eclipse such a big deal? (5:23 min)

7. View Animations
health/2017/7/25/ /solar-ecIn zip code
In zip code 67052 , you will see a partial solar eclipse.
The eclipse will peak at 1:03:44 pm CDT, when the moon obscures 92.2% of the sun.

8. Total solar eclipse geometry showing path of umbral shadow (or totality).

9. Totality
Bailey’s Beads

10. You will also be able to see 4 planets at totality

11. Total Solar Eclipse Helped Prove Einstein Right About Relativity
1919 Solar Eclipse – Proving General Relativity
On May 29, 1919, British astronomer, Sir Arthur Eddington headed two British Expeditions to Sobral, Brazil and Principe, West Africa, to confirm Einstein's predictions from his general theory of relativity that the path of a light ray would be bent in the presence of a strong gravitational field. The goal was to measure the positions of stars just off the limb of the sun (impossible to do under normal sunny day conditions) and to see if their apparent positions would indeed be altered by the sun’s enormous gravitational field (fig e). Five stars were selected and photographed. Their positions were compared with pictures taken of the same star field before the eclipse. The results agreed with Einstein’s predictions both qualitatively (yes, the stars positions did change) and quantitatively (they changed by the predicted amount).
Oh leave the Wise our measures to collate One thing at least is certain, LIGHT has WEIGHT One thing is certain, and the rest debate -- Light-rays, when near the Sun, DO NOT GO STRAIGHT. - Arthur S. Eddington (1920)

12. Be sure to have your solar glasses on when it begins to move past totality
Total solar eclipse just prior to totality. Reddish prominences can be seen off the sun’s limb.

13. Interactive Map
MapFull.html

14. Solar Eclipse August 11, 1999 Soissons, France
…but the clouds parted just enough to catch these photos of the partial phase. During totality, the sky was overcast but you could tell totality had started because the light level dropped very quickly.

15. Fun Eclipse Facts
The moon’s shadow moves at 1700 km/hour (1,048 mi/hr) .
Maximum totality is ~7 ½ minutes.
Every place on Earth will see a total solar eclipse about every 400 years.
Solar Eclipses occur more frequently than lunar eclipses ( by 5:3).
There must be at least two solar eclipses every year.
There can be two solar eclipses in back to back months with a total lunar eclipse in between.
This triple eclipse can occur twice during an eclipse year (1935, 2160).
Seven eclipses is the maximum - 4 solar, 3 lunar (1982, 2485).

16. Map of the Earth showing the path of totality for all eclipses between 2001 and Notice that there are two eclipses (2017 and 2024) that can be seen in totality over the United States.