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Solar Eclipse Cycles and Saros
Module 1
The Three Lunar Clocks Behind Eclipse Recurrence
1
Types of Lunar Months and Their Astronomical Alignments
Distinguish the synodic, draconic, and anomalistic months by the astronomical alignment each one measures.
Distinguish the synodic, draconic, and anomalistic months by the astronomical alignment each one measures.
2
Why Similar Eclipses Require Matching Phase, Node, and Distance
Explain why a similar eclipse requires the Moon to return near the same phase, orbital node, and Earth–Moon distance at once.
Explain why a similar eclipse requires the Moon to return near the same phase, orbital node, and Earth–Moon distance at once.
3
How Unequal Lunar Months Re-align Over Time
Explain conceptually how unequal lunar month lengths can nevertheless return to a close alignment after many orbits.
Explain conceptually how unequal lunar month lengths can nevertheless return to a close alignment after many orbits.
Module 2
How the Saros Cycle Works
4
The Saros Cycle: Aligning Lunar Months and Eclipse Patterns
Interpret the near equality of 223 synodic months, 242 draconic months, and 239 anomalistic months as the basis of the Saros cycle.
Interpret the near equality of 223 synodic months, 242 draconic months, and 239 anomalistic months as the basis of the Saros cycle.
5
Why the Saros Cycle Lasts 18 Years, 11 Days, and 8 Hours
Explain why one Saros lasts about 18 years, 11 days, and 8 hours.
Explain why one Saros lasts about 18 years, 11 days, and 8 hours.
6
How Eight Extra Hours Shift the Next Eclipse One-Third Around Earth
Explain how the extra eight hours shift the next eclipse about one-third of the way around Earth in longitude.
Explain how the extra eight hours shift the next eclipse about one-third of the way around Earth in longitude.
7
What Repeats and Changes After One Saros Cycle
Identify which characteristics of an eclipse recur after one Saros and which do not repeat exactly.
Identify which characteristics of an eclipse recur after one Saros and which do not repeat exactly.
Module 3
Saros Series and Related Cycles
8
The Evolution of Eclipses Through a Saros Series
Describe how successive eclipses in a Saros series evolve from polar partial eclipses through central eclipses and back to polar partial eclipses.
Describe how successive eclipses in a Saros series evolve from polar partial eclipses through central eclipses and back to polar partial eclipses.
9
Why Multiple Saros Series Create Interleaved Eclipse Sequences
Explain why many Saros series coexist and produce an interleaved sequence of eclipses.
Explain why many Saros series coexist and produce an interleaved sequence of eclipses.
10
Saros, Eclipse Season, and Exeligmos: Timescales and Prediction
Distinguish the Saros from an eclipse season and the three-Saros exeligmos by timescale and predictive use.
Distinguish the Saros from an eclipse season and the three-Saros exeligmos by timescale and predictive use.