July 1916 lunar eclipse

July 1916 lunar eclipse

Partial eclipse
The Moon's hourly motion shown right to left
Date	July 15, 1916
Gamma	−0.5957
Magnitude	0.7944
Saros cycle	118 (46 of 74)
Partiality	172 minutes, 30 seconds
Penumbral	292 minutes, 24 seconds
Contacts (UTC) P1 2:19:36 U1 3:19:33 Greatest 4:45:49 U4 6:12:03 P4 7:12:00
← January 1916 January 1917 →

A partial lunar eclipse occurred at the Moon’s ascending node of orbit on Saturday, July 15, 1916,^[1] with an umbral magnitude of 0.7944. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A partial lunar eclipse occurs when one part of the Moon is in the Earth's umbra, while the other part is in the Earth's penumbra. Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. Occurring only about 3.5 hours after perigee (on July 15, 1916, at 1:15 UTC), the Moon's apparent diameter was larger.^[2]

The Ross Sea party was a component of Sir Ernest Shackleton's Imperial Trans-Antarctic Expedition of 1914–17. Five men were stranded not far away from Cape Evans. There was sea ice between them and the relative safety of the hut on Cape Evans. On May 8 two of the men, Aeneas Mackintosh and Victor Hayward, decided to make an attempt to reach the hut. Soon after they set out, a blizzard hit. When the weather cleared up, the remaining men tried to look for them, but realized that the ice was far too thin to cross, and that their friends had been lost. Now they knew that they should wait for a thicker ice and for the full moon to attempt the crossing. Having the full moon was essential, because during polar night the moon is the only source of natural light other than the extremely dim light of the stars.

The weather did not cooperate during the full moon of June, but on July 15, everything seemed to be just right: calm weather, thick ice, clear skies and a full moon. The men started their journey in the morning. When the moon rose, however, the men were surprised to find it was about to be eclipsed^{[citation needed]}. Ernest Wild wrote later:

"I thought we were going to be left in darkness but a very little bit of the rim remained to light us..."

Although the eclipse continued for a few hours, the men were fortunate because it was only a partial eclipse. They reached Cape Evans later on the same day.^[3]

The eclipse was completely visible over eastern North America, South America, and Antarctica, seen rising over western North America and the central Pacific Ocean and setting over Africa and western Europe.^[4]

Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.^[5]

July 15, 1916 Lunar Eclipse Parameters

Parameter	Value
Penumbral Magnitude	1.73508
Umbral Magnitude	0.79437
Gamma	−0.59568
Sun Right Ascension	07h36m32.1s
Sun Declination	+21°35'52.3"
Sun Semi-Diameter	15'44.1"
Sun Equatorial Horizontal Parallax	08.7"
Moon Right Ascension	19h37m12.9s
Moon Declination	-22°11'11.4"
Moon Semi-Diameter	16'43.6"
Moon Equatorial Horizontal Parallax	1°01'23.4"
ΔT	18.8 s

This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.

Eclipse season of July 1916

July 15 Ascending node (full moon)	July 30 Descending node (new moon)
Penumbral lunar eclipse Lunar Saros 118	Annular solar eclipse Solar Saros 144

• A partial lunar eclipse on January 20.
• A total solar eclipse on February 3.
• A partial lunar eclipse on July 15.
• An annular solar eclipse on July 30.
• A partial solar eclipse on December 24.

• Preceded by: Lunar eclipse of September 26, 1912
• Followed by: Lunar eclipse of May 3, 1920

• Preceded by: Lunar eclipse of June 4, 1909
• Followed by: Lunar eclipse of August 26, 1923

• Preceded by: Solar eclipse of July 10, 1907
• Followed by: Solar eclipse of July 20, 1925

• Preceded by: Lunar eclipse of August 15, 1905
• Followed by: Lunar eclipse of June 15, 1927

• Preceded by: Lunar eclipse of July 3, 1898
• Followed by: Lunar eclipse of July 26, 1934

• Preceded by: Lunar eclipse of August 3, 1887
• Followed by: Lunar eclipse of June 25, 1945

• Preceded by: Lunar eclipse of September 13, 1829
• Followed by: Lunar eclipse of May 16, 2003

Lunar eclipse series sets from 1915 to 1918

Descending node				Ascending node
Saros	Date Viewing	Type Chart		Saros	Date Viewing	Type Chart
103	1915 Jan 31	Penumbral		108	1915 Jul 26	Penumbral
113	1916 Jan 20	Partial		118	1916 Jul 15	Partial
123	1917 Jan 08	Total		128	1917 Jul 04	Total
133	1917 Dec 28	Total		138	1918 Jun 24	Partial
143	1918 Dec 17	Penumbral

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A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).^[6] This lunar eclipse is related to two annular solar eclipses of Solar Saros 125.

July 10, 1907	July 20, 1925

• List of lunar eclipses
• List of 20th-century lunar eclipses

• The Monthly Evening Sky Map, Volumes 9-11 Partial Lunar Eclipse of July 14–15, 1916
• Kelly Tyler-Lewis (2007). The Lost Men: The Harrowing Saga of Shackleton's Ross Sea Party. Penguin Publishing Group. p. 206. ISBN 978-1-4406-2858-0.

• 1916 Jul 15 chart Eclipse Predictions by Fred Espenak, NASA/GSFC