1. The Great American Eclipse
August 21, 2017

2. Solar Eclipse
When Moon’s shadow hits the Earth

3. Light sources and shadows
Large light source
Produces large ‘fuzzy’ shadow.
Dark central area smaller than object
Light
Some light
No light
Some light
Light

4. Fuzzy shadow patterns
Umbra
Umbra
Penumbra
Umbra

5. Moon’s shadow When cast on Earth
Central dark area (umbra) will be ~80 miles across
Moves across Earth’s face at ~2000 mph
Only small area experiences this for a short time.
Much larger area experiences ‘fuzzy shadow’ (penumbra)

6. Total Eclipse
As shadow crosses face of Earth it traces out the ‘Path of Totality’.

7. Monday, August 21, 2017

8. Jacksboro Middle School - Monday, August 21, 2017}
MUST use eclipse glasses or viewer
(To nearest second - times vary slightly depending on exact location.)
1:04:00 pm –1st Contact (C1)
Partial Eclipse starts
2:33:25 pm – Maximum eclipse
99.3% covered
3:57:42 pm – 4th Contact (C4)
Partial Eclipse ends

9. 99.3% partial eclipse Only thin crescent remains visible
Must still use eye protection or viewer
Will get noticeably darker
Weird-looking shadows
Will NOT see dark sky or Sun’s corona

10. Safe Viewing MUST use special glasses or pinhole viewer.
During partial phases (Any time Sun is not completely blocked.)
MUST use special glasses or pinhole viewer.
Only total eclipse is safe to view directly without protection

11. Pinhole projector - basics

12. Pinhole ‘viewer’

13. Cereal box ‘viewer’

14. Pinhole ‘viewer’

15. Pinhole ‘viewer’

16. Total Eclipse
Viewed from within the path of totality, the Moon completely blocks the main body of the Sun.
Looks like a ‘black hole’ in the sky!
Can see planets and stars
Animals and plants behave as if it’s night.

17. Total Eclipse Reveals details of the Sun’s ‘atmosphere’ Corona
Normally too dim to see
Important to study for very practical reasons.
Corona
Chromosphere

18. Diamond Ring Effect
Last patch of bright light shines through valley on edge of Moon.
Watch short movie of 1994 eclipse

19. TTU Tucker Stadium - Monday, August 21, 2017
(To nearest second - times vary slightly depending on exact location.)
12:01:15 pm –1st Contact (C1)
Partial Eclipse starts
1:29:43 pm – 2nd Contact (C2)
Total Eclipse begins
1:32:15 pm – 3rd Contact (C3)
Total Eclipse ends
2:56:00 pm – 4th Contact (C4)
Partial Eclipse ends }
MUST use eclipse glasses or viewer }
Can view safely with naked eye }
MUST use eclipse glasses or viewer

21. Solar system model

23. Earth - Sun distance Slightly closer in winter!
Insignificant effect on climate.
(Note: This is a factor for some planets, but NOT Earth!)
So why is it warmer in summer for us?
Do rest of activity.