1. The Great American Eclipse Welcome Back to School!
Aug. 21, 2017

2. Great American Eclipse: August 21, 2017

3. #1 – It Doesn’t Happen Every Day…In Fact:
So What’s The Big Deal?
#1 – It Doesn’t Happen Every Day…In Fact:
Last total solar eclipse on any U.S. soil – 1991
Hawaii only
Last anywhere in Continental U.S. – 1979
WA, OR, ID, MT, ND
Last to go across the U.S. – 1918
Last in St. Louis – (Next time: 2505)
Annular eclipse in May 1994
As you can see, solar eclipses are quite rare. Even though, on average, two solar eclipses take place each year, eclipse paths are narrow, and the earth large.
Slide courtesy of John Wharton, SLSC

4. St Louis Solar Eclipses
Between 1700 and 2100 AD, there were/will be 153 solar eclipses visible from St Louis.
Of these 153 eclipses, one is total, three are annular and the rest are partial.
That is an average of 3.8 eclipses per decade.
However, a given location will only average one total eclipse roughly every 375 years (Meeus 1997).
Reference:

5. Slide courtesy of John Wharton, SLSC
They occur when just the right alignment in the paths of the earth and moon with the sun takes place, where a shadow of the moon is cast directly onto the earth.
Slide courtesy of John Wharton, SLSC

6.
Short little video to show why there are so few total eclipses.
1:28 minutes

7. Due to lack of perfect alignment, there are not solar or lunar eclipses every month.
1442
1994
Even when the moon crosses directly in front of the sun, it has to be at the right distance for a true total eclipse to be seen.
Slide courtesy of John Wharton, SLSC

8. World Total Eclipse 2017
The eclipse path does NOT touch any significant landmass outside the U.S.
Totality will take 1h 30m 30s to cross the entire U.S.
Southern Illinois will have the longest duration of Totality 2m 40.2s
Partial Eclipse visible from Arctic Circle to South America

9. Path of Totality Missouri and Illinois
Map: Fred Espenak,

10. Totality lasts 1 minute and 50 seconds.
In Columbia, IL:
Eclipse starts at 11:50.05
Totality starts at 1:17.38
Totality ends at 1:19.28
Totality lasts 1 minute and 50 seconds.
Eclipse ends at 2:44.37

11. What Will Happen Around You at Totality
Sky changes in brightness and color
Shadows become sharper
“Shadow bands” may be visible
Temperature drops 5-15 degrees
Winds may increase
Some animals behave as if it’s night
Brightest stars and planets become visible
A total eclipse can be a complete sensory experience.
Slide courtesy of John Wharton, SLSC

12. Onset of Totality (totality begins at 1:17:38 pm)
Bailey’s Beads (about seconds before totality)
Diamond Ring
Diamond ring announces onset of totality;
Eye protection needed until “Totality”
“Totality” begins at 1:17:38 pm
Sky gets deeper and deeper blue
Shadows become impossibly clear, thin
Last bit of Sun’s light glare through valleys of Moon
Photo credit: Arief R. Sandan (Ezagren) March 9, 2016 Indonesia
Photo credit: Fred Espenak

13. 1:16pm
1:17pm
1:18pm
Observe “Bailey’s beads” and the diamond ring effect as the last portion of the Sun’s surface disappears behind the valleys of the Moon. Both of these because the moon is not flat. Some light gets through the edge of the moon. The diamond ring effect happens when a single point of sun shines through a valley on the moon.
Immediately after the diamond ring, observers can be told they can observe the Sun without eclipse glasses. (Time for that is 1:17.38 to 1:19.28 p.m.)
Observers should look at the corona, and look for bright planets and stars near the Sun.
The spectacle takes up to a few hours to play out, from “first contact” of the moon’s limb touching the sun, to complete totality at mid-point, to “last contact”. At totality, you’re able to see the glowing solar atmosphere or “corona” against a darkened sky, without the blinding light of the sun’s disc.

15. What to look for during Totality
Mid-Totality – with the Moon’s shadow centered over your location, observe the horizon 360° around, see the glowing horizon extending beyond the limits of the shadow.
Observe the ghostly outer and inner Solar atmosphere.
Observe the reddish-pink flames of the Solar Prominences extending above the Sun’s surface.
Four planets may be visible.

16. Planets that may be visible during total solar eclipse: Jupiter, Mars, Venus, and Mercury. Mercury is very close to the sun, so will be hard to see

17. Constellations that are up during eclipse time
Constellations that are up during eclipse time. Parts of these may be visible.

18. What to look for during Totality
Totality Ends - The horizon will brighten to the west as the shadow’s edge approaches.
Observers must be reminded to start using eclipse glasses again
The reverse diamond ring will occur.

19. 2 hour 55 minute event First contact 11:50:05 am
Fourth contact 2:44:37 pm

20. How to Observe The Eclipse

21. CAUTION!
The ONLY time you can safely look directly at the sun without your solar glasses is when it’s TOTALLY eclipsed. Even a momentary glimpse at the partially-covered sun can damage your eyes!
The ONLY absolutely safe way to view the partially-eclipsed sun is indirectly (such as with “pin-hole” projection).
A TOTALLY eclipsed sun is the only sun you can view with your naked eyes. Otherwise, any partial-eclipse phase must be viewed indirectly!
Slide courtesy of John Wharton, SLSC

23. When to wear solar glasses?
This is true: The sun is bad for your eyes. So, when you look at the sun, you need to be wearing your solar glasses to protect their eyes while looking at it.
If the sun is not visible, only the moon and the corona is, you may take your glasses off. You should take your glasses off during this time to see all of what is visible during totality.

24. Your certified eclipse glasses should not be used with binoculars, cameras, or telescopes as concentrated sunlight will make solar filters unsafe.
Do NOT use your cell phones to take pictures during the solar eclipse. The concentrated sunlight coming through your cell phone lens will also make the solar filter unsafe.

25. References US Outline Map
Sky Map and Missouri Phase Maps
NASA Timing Data
Missouri Path Map
NASA Eclipse Shadow Cones
Special thanks to Dr. Bob Brazzle, physics teacher at Jefferson college, for letting me incorporate part of his SLAAPT association meeting power point into this presentation.

26. Other webpages:
Interactive map to show times for regions in U.S.
Safe solar viewing techniques:
Filters:
AstroSolar.com Page has instructions on how to build your own solar filters for camera, telescope, and/or binoculars
General:
Eclipse2017.org has an app that works with the eclipse. It also has MANY videos and other tools you can use.
eclipse2017.nasa.gov