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Expert: - 12/13/2004


Question
What exactly is a "Saros cycle" in layman's terms please,

Thank you!
Lola

Answer
Hi Lola,
 Yes, it's simply the time it takes for the moon to return
back to almost its exact same position in our sky....
equal to 6585.3 days, or 18 years, 10 days, and 8 hours later.

Even the ancients knew of this repeating moon cycle.


It's important in predicting eclipses....for instance, we know
that Europe had a total solar eclipse on August 11, 1999....
so we automatically know that another almost identical
total solar eclipse will occur 18 years, 10 days and 8 hours
later....on August 21, 2017....BUT
And here is where the 8 hours is important;  The earth will
rotate eastward 8 hours, or 120 degrees of rotation, so
not Europe, but the USA will get the eclipse on 8/21/2017.
It will not return to European soil until another 54 years,
31 days after 8/11/99, or on or about Sept 12, 2053.

I remember watching the total solar eclipse in Perry FLA
as it went up the East Coast of the USA on March 7, 1970
....add 54 years and 31 days to that figure, and you
will get a total solar eclipse up the Mississippi and Ohio
valley's on April 8, 2024....not quite exactly where it was
originally, but pretty close.
As I said, the moon *almost* back to its exact same position
in our sky.

Hope all this helps,
Clear Skies,
Tom Whiting
Pres...ECMOG
Erie, PA

Astronomy

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Tom Whiting

Expertise

Astronomy has been my hobby/pasttime for over 50 years.  Currently own 3 telescopes, the largest of which is a 30 inch Newtonian truss Dob that is portable.I taught Astronomy/Meteorology at the University Level for 13 years before retiring in 1995. Being retired and home most of the time, I am able to answer all questions relatively quickly, unless it's a new moon weekend with good observing conditions.  No astrology questions please, or questions about alleged UFO picture identifications.

Experience

Experience: Astronomy has been my hobby and study for over 50 years. We currently now own a 30 inch portable telescope (Updated - Pennsylvania`s largest portable telescope). It can be seen on our website at:http://www.velocity.net/~bwhiting and also attend several regional starparties during the year, and have been on 5 total solar eclipse expeditions.

Organizations: President, Erie County Mobile Observers Group for over 15 years.

Publications: Wrote the "Over Erie Skies" newspaper article in our local newspaper for 11 years (1975-86).

Education: Masters Degree- Taught at the University level for 13 years. Retired 20 years -USAF Pilot - KC-135 with 180 combat missions;  Also Eagle Scout, Philmont staff 2 Yrs, Order of Arrow Lodge Chief, Ham Radio (inactive).

Awards: two discoveries: The mini-coathanger asterism in Ursa Minor (the little dipper) And the mini-ladle- another asterism in the bowl of Ursa Minor. Clients: Currently President of the ECMOG as mentioned above.

Education/Credentials
BS  Metallurgical Engineering Grove City College, PAMaster's Degree, Gannon University, Erie, PA Also retired USAF pilot, 20 years.

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