1. The Great American Solar Eclipse 8/21/2017
Academy for Life Long Learning
April 18, 2017
Gary J. Senn, PhD -

2. What is an eclipse?
Eclipse: Obscuring of one solar body. It is all in the name.
Solar Eclipse: Sol or the Sun
Lunar Eclipse: Luna or the Moon
- SME
- SEM

3. Eclipse Resources
Credit: Rick Fienberg / TravelQuest Int'l. / Wilderness Travel.

4. How do eclipses occur? Lunar eclipse Solar eclipse Moon phase? Order?
Full moon
Order?
SEM
Solar eclipse
New moon
SME

5. Types of eclipses
Partial
Total
Annular
Hybrid

6. Lunar eclipse from space
Image Credit:

7. Solar eclipse from space
Image Credit: Wikimedia Commons

8. How often do eclipses occur?
Why not every month?
Image Credit: AstronomyOnline.org

9. Saros series - Series of eclipses
Chaldeans BC
Background - types of months
Sidereal Month (star to star) = days = 27d 7h 43m 11.5 s
Synodic Month (new moon to new moon) = days = 29d 12h 44m 03s
Anomalistic Month (perigee to perigee) = days = 27d 13h 18m 33s
Draconic Month (node to node) = days = 27d 05h 05m 36s
Sidereal month days (27 d 7 h 43 min 11.5 s). Time to get back to the same spot in the sky
Latin = Sidera. English = Stars
Synodic month –
Latin = Synod. English = Meeting
Anomalistic month
Anomoly – something different or abnormal – going from perigee to perigee is abnormal from the observer’s perspective
Draconic month – or Nodical month. Named for the dragons that live in the nodes and eat the sun or moon during eclipses

10. Saros series One cycle in series repeats every:
6,585.3 days (18 years 11 days 8 hours)
223 Synodic Months = days = 6585d 07h 43m
239 Anomalistic Months = days = 6585d 12h 54m
242 Draconic Months = days = 6585d 08h 35m

11. Saros Series Characteristics
Duration: 1226 – 1550 years
Number of Eclipses: 69-87
Odd Saros Numbers: Solar Eclipse
Near Moon’s ascending node
Begins near north pole
Shift southward
Even Saros Numbers: Solar Eclipse
Opposite
Moon, opposite from Sun

12. Saros 145 – 8/21/17 Eclipse Began 1639 – partial near north pole
First Annular 1891
First total 1927
Last total 2648
End 3009 – partial near south pole
Series of , 1909, 1927, 1945, 1963, 1981, 1999, 2017, 2035 and 2053

14. Saros 136 – longest eclipses of 20th and 21st centuries
Even number – South to North

15. Saros 145 Includes 8/21/2017 Eclipse Odd number – North to South
greatamericaneclipse.com

16. 21st Centurey Solar Eclipses

17. 21st Century Solar Eclipses