Wednesday, July 25, 2018

July 27, 2018, Total Lunar Eclipse Belongs to Saros Cycle 129


Summary: The Friday, July 27, 2018, total lunar eclipse belongs to Saros cycle 129, a series of 71 lunar eclipses linked by similar geometries.


Fred Espenak and Jean Meeus/Five Millennium Canon of Lunar Eclipses via NASA Eclipse Web Site

The Friday, July 27, 2018, total lunar eclipse belongs to Saros cycle 129, which consists of a series of 71 lunar eclipses linked by similar geometries over a cycle of approximately 6,585.3 days (18 years 11 days 8 hours).
Saros 129 lunar eclipses share occurrences at the lunar orbit’s descending node. Also known as the lunar orbit’s south node, the descending node marks the point of the moon’s crossing from north to south of the Earth’s orbital plane.
July 2018’s total lunar eclipse appears as number 38 in the lineup of Saros 129 lunar eclipses. The family, known as a series, of Saros 129 endures for 1,262.11 years. Saros 129 opens Thursday, June 10, 1351, with a penumbral eclipse in proximity to the southern edge of the fainter, outer part of Earth’s shadow, known as the penumbra (Latin: paene, “almost, nearly” + umbra, “shadow”). Saros 129 closes Saturday, July 24, 2613, with a penumbral eclipse tapping the penumbra’s northern edge.
Saros 129’s lineup of 71 lunar eclipses undergo five sequences. The initial sequence is composed of 10 penumbral eclipses. The second sequence comprises 21 partial eclipses. The third sequence features 11 total eclipses. The fourth sequence presents 21 partial eclipses. The fifth and final sequence consists of eight penumbral eclipses.
The total lunar eclipse Friday, July 27, 2018, holds seventh place in the sequence of 11 total lunar eclipses. The sequence’s first total lunar eclipse occurred Tuesday, May 24, 1910. The sequence’s last total lunar eclipse happens Thursday, Sept. 8, 2090.
Retired NASA astrophysicist Fred Espenak, known as “Mr. Eclipse,” details phase durations for July 2018’s Saros 129 on NASA’s Eclipse website. The penumbral phase covers 373.8 minutes. Partiality lasts 234.5 minutes. Totality spans 103.0 minutes.
Saros 129’s first total lunar eclipse, occurring Tuesday, May 24, 1910, displayed a penumbral phase of 360.3 minutes. Partiality spanned 215.4 minutes. May 1910’s Saros 129 total eclipse presented 35.9 minutes of totality. The May 1910 event occupied place 32 in Saros 129’s lineup of 71 lunar eclipses.
Saros 129’s final total lunar eclipse anticipates a penumbral phase of 362.0 minutes. The Sept. 8, 2090, total lunar eclipse expects a partiality duration of 213.1 minutes. Totality endures 31.9 minutes. The September 2090 event holds place 42 in Saros 129’s lineup of 71 lunar eclipses.
Saros 129’s total lunar eclipse of Sunday, July 16, 2000, claims longest duration of totality, at 1 hour 46 minutes 24 seconds, in the sequence of 11 total lunar eclipses. July 2000’s lunar event occurred as the sequence’s sixth total lunar eclipse and as number 37 among Saros 129’s lineup of 71 lunar eclipses.
January 2018’s Saros 124 total lunar eclipse ranks as third longest in the 11-event sequence’s totality phase duration. The second longest totality phase occurred during the sequence’s Tuesday, July 6, 1982, total lunar eclipse. July 1982’s totality spanned 105.7 minutes.
Saros 129’s total lunar eclipse of Thursday, Sept. 8, 2090, closes the sequence with the shortest predicted duration of totality, at 00 hours 31 minutes 51 seconds. The sequence’s opening total lunar eclipse of Tuesday, May 24, 1910, claims the second shortest duration of totality, at 49.5 minutes.
July 2018’s immediate predecessor in Saros 129’s total lunar eclipse sequence occurred Sunday, July 16, 2000. July 2018’s successor in the sequence happens Thursday, Aug. 7, 2036.
July 2018’s total lunar eclipse is the second of the year’s two total lunar eclipses. The year’s first total lunar eclipse happened Wednesday, Jan. 31. January’s total lunar eclipse belonged to Saros 124.
The takeaways for the July 27, 2018, total lunar eclipse are that the event appears as seventh in Saros cycle 129’s sequence of only 11 total lunar eclipses and that July 2018’s totality phase of 103.0 minutes ranks as the sequence’s third longest totality duration.

total lunar eclipse Sunday, July 16, 2000, longest Saros cycle 129 totality phase: Fred Espenak and Jean Meeus/Five Millennium Canon of Lunar Eclipses via NASA Eclipse Web Site

Acknowledgment
My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:
Friday, July 27, 2018, total lunar eclipse (Saros cycle 129): Fred Espenak and Jean Meeus/Five Millennium Canon of Lunar Eclipses via NASA Eclipse Web Site @ https://eclipse.gsfc.nasa.gov/5MCLEmap/2001-2100/LE2018-01-31T.gif
The total lunar eclipse Sunday, July 16, 2000, claims the Saros cycle 129 record for longest totality phase, with a duration of 1 hour 46 minutes 24 seconds: Fred Espenak and Jean Meeus/Five Millennium Canon of Lunar Eclipses via NASA Eclipse Web Site @ https://eclipse.gsfc.nasa.gov/5MCLEmap/1901-2000/LE2000-07-16T.gif

For further information:
Dickinson, David. “Predicting Eclipses: How Does the Saros Cycle Work?” Universe Today > Guide to Space. March 26, 2015. Updated Dec. 23, 2015.
Available @ https://www.universetoday.com/119444/predicting-eclipses-how-does-the-saros-cycle-work/
Espenak, Fred. “Catalog of Lunar Eclipse Saros Series.” NASA Eclipse Web Site > Lunar Eclipses > Lunar Eclipse Catalogs.
Available @ https://eclipse.gsfc.nasa.gov/LEsaros/LEsaroscat.html
Espenak, Fred. “Eclipses and the Saros.” NASA Eclipse Web Site.
Available @ https://eclipse.gsfc.nasa.gov/SEsaros/SEsaros.html
Espenak, Fred. “Eclipses During 2018.” EclipseWise > Recent and Upcoming Lunar Eclipses.
Available @ http://www.eclipsewise.com/oh/ec2018.html
Espenak, Fred. “Key to Saros Catalog of Lunar Eclipses.” EclipseWise > Lunar Eclipses > Saros -29 to 190.
Available @ http://www.eclipsewise.com/lunar/LEhelp/LEsarcatkey.html
Espenak, Fred. “Periodicity of Lunar Eclipses.” NASA Eclipse Web Site > Lunar Eclipses > Special Interest > Eclipses and the Saros.
Available @ https://eclipse.gsfc.nasa.gov/LEsaros/LEperiodicity.html
Espenak, Fred. “Saros Series 129.” EclipseWise > Recent and Upcoming Lunar Eclipses > Eclipses During 2018.
Available @ http://www.eclipsewise.com/lunar/LEsaros/LEsaros129.html
Espenak, Fred. “Total Lunar Eclipse of July 27.” EclipseWise > Lunar Eclipses > Eclipses During 2018.
Available @ http://www.eclipsewise.com/oh/ec2018.html#LE2018Jul27T
van den Bergh, George. Periodicity and Variation of Solar (and Lunar) Eclipses. Haarlem, Netherlands: H.D. Tjeenk Willink, 1955.

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