Earth and Space News: June 1918 total solar eclipse

Showing posts with label June 1918 total solar eclipse. Show all posts

Wednesday, July 21, 2021

Howard Butler and Herbert Tschudy Drew June 8, 1918, Total Solar Eclipse

Summary: Artists Herbert Tschudy and Howard Butler drew the June 8, 1918, total solar eclipse from their respective observation sites in Colorado and Oregon.

Artists Herbert Tschudy and Howard Butler drew the June 8, 1918, total solar eclipse from their respective observation sites in Boulder, north central Colorado, and Baker City, southeastern Oregon.

American landscape and portrait painter Herbert Bolivar Tschudy (Dec. 28, 1874-April 15, 1946) witnessed the Saturday, June 8, 1918, total solar eclipse as museum artist for New York's Brooklyn Museum. He was museum artist from 1899 to 1925 and spelled his surname as Judy until 1914, according to the museum's finding aid, Guide to the Records of the Departments of European Painting and Sculpture, American Painting and Sculpture, Contemporary Art 1897-2005 (page 5). In 1925, he became Brooklyn Museum's Curator of Painting and Sculpture. Then, from September 1934 through December 1936, he was the museum's Curator of Contemporary Art. He was Curator Emeritus from January 1937 until his death in April 1946.

Tschudy reported his observation of the June 1918 solar eclipse in the July 1918 issue of The Brooklyn Museum Quarterly. He noted the rarity of the eclipse's visibility across the United States, from Washington in the northwest to Florida in the southeast. Such conditions would not ". . . prevail again in the United States for a hundred years" (page 129). Indeed, the next Pacific-to-Atlantic traversal of the contiguous United States, known as the Great American Eclipse, did not take place until Monday, Aug. 21, 2017.

Tschudy's original expectation was that he would make his observations from Colorado's state capital, Denver. North central Colorado's Mile High City's unfavorable weather conditions, however, occasioned his nearby relocation to Boulder, to a promontory opposite Mt. Lookout. The lack of "clear weather" made the sun invisible and the solar eclipse a "failure" in Denver (pages 130, 132). Fortunately, Tschudy's observation site in the mountains at Boulder gave him a satisfactory view, even though ". . . a film of cloud . . . partially obscured the sun at totality . . ." (page 131).

Tschudy noted color and temperature changes announcing the approach of the eclipse's maximum phase, totality. The blue sky transitioned to "warm indigo" while black, low rain clouds contrasted with the western and northern horizon's "sulphur yellow and burnt orange" (page 131). He described the darkened sun's ashening of his observation site as wrapping plants and rocks "in a cloak of death" (page 131). He equated the darkness to ". . . the ominous gloom of an impending storm at sunset . . ." (page 132).

Time and Date website gives local circumstances for the June 1918 solar eclipse at Boulder, Colorado. The solar event's partial eclipse began, with lunar contact with the edge of the solar disk, at 4:10:54 p.m. Mountain Daylight Time (22:10:54 Coordinated Universal Time; 6:10 p.m. Eastern Daylight Time). The solar event's total phase began, with total obscuration of the sun, at 5:21:54 p.m. MDT (23:21:54 UTC; 7:21 p.m. EDT). Maximum eclipse, with the lunar disk closest to the sun's center, took place at 5:22:33 p.m. MDT (23:22:33 UTC; 7:22 p.m. EDT). The solar event's total eclipse ended at 5:23:11 p.m. MDT (23:23:11 UTC; 7:23 p.m. EDT). The Saturday, June 8, 1918, solar eclipse completed its partial eclipse at 6:26:44 p.m. MDT (Sunday, June 9, at 00:26:44 UTC; Saturday, June 8, at 8:26 p.m. EDT).

American landscape and portrait painter Howard Russell Butler (March 3, 1856-May 20, 1934) witnessed the Saturday, June 8, 1918, total solar eclipse as a member of the United States Naval Observatory's Eclipse Expedition. He reported his experience and detailed his technique in March 1919 issue of Natural History.

Butler's observation site was southeastern Oregon's Baker City. The observation station was located in the fair grounds, about one and one-half miles from the town's center.

Butler's painted capture of the total solar eclipse represented the first rendition of the solar corona from direct observation. He noted that the time constraint of 112 seconds contrasted with his usual portrait time frame of ". . . ten or twelve sittings of two hours each . . ." (page 264).

Cloudiness at first contact, at 2:47 p.m., seemed to preclude observation of the event. Fortunately, cloud thinning at 3:30 p.m. transitioned to blue sky to the right of the sun at 3:50 p.m. The sky then cleared rapidly until only a thin cloud covered the sun. Despite disappointment at the absence of a cloudless setting, Butler noted the artistic advantage of picturesque mystery created by the coronal burning ". . . through the thin veil as if it were not there" (page 270). Butler's color observations included pinkish and fiery red prominences, greenish- and yellowish-toned outer corona, and glowing rose-colored lower right limb. Baily's beads, in which the moon's jagged topography breaks sunlight into beads, awed Butler with the appearance of ". . . a miniature sun radiating in all directions" (page 271).

Time and Date website gives local circumstances for the June 1918 solar eclipse at Baker City, Oregon. The solar event began with a partial eclipse at 2:46:57 p.m. Pacific Daylight Time (21:46:57 UTC; 5:46 p.m. EDT). The solar eclipse's total eclipse started at 4:03:54 p.m. PDT (23:03:54 UTC; 7:03 p.m. EDT). The total eclipse reached maximum eclipse at 4:04:50 p.m. PDT (23:04:50 UTC; 7:04 p.m. EDT). The total eclipse ceased at 4:05:46 p.m. PDT (23:05:46 UTC; 7:05 p.m. EDT). The Saturday, June 8, 1918, solar eclipse closed its partial eclipse at 5:15:10 p.m. PDT (Sunday, June 9, at 00:15:10 UTC; Saturday, June 8, at 8:15 p.m. EDT).

The takeaways for June 8, 1918, total solar eclipse drawings by Howard Butler and Herbert Tschudy are that the two American artists portrayed the solar event from their respective observation sites in Baker City, southeastern Oregon, and Boulder, north central Colorado; that the thin cloud veiling of the eclipse did not interfere with Butler's or Tschudy's artistic renderings; and that almost 100 years elapsed between Butler's and Tschudy's June 1918 solar artworks and August 2017, the next all-visibility of a total solar eclipse across the entire contiguous United States.

Acknowledgment

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

Image credits:

colored crayon drawing of Saturday, June 8, 1918, total solar eclipse, viewed from Boulder, north central Colorado, by American landscape and portrait artist Herbert Bolivar Tschudy (Dec. 28, 1874-April 15, 1946); Brooklyn Museum Quarterly (July 1918), opposite page 129: Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Brooklyn_Museum_Quarterly_(1916)_(14773320231).jpg; Not in copyright, via Internet Archive @ https://archive.org/details/brooklynmuseumqu46broouoft/page/n409/mode/1up

view of Saturday, June 8, 1918, total solar eclipse from Baker City, southeastern Oregon, by American landscape and portrait painter Howard Russell Butler (March 3, 1856-May 20, 1934): Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:HowardRussellButlerEclipse.JPG; Open Access, CC BY 4.0 International, via Apollo -- University of Cambridge Repository @ https://www.repository.cam.ac.uk/items/ae547389-73ef-4e5a-9101-b7e5f082fced

For further information:

Abbot, C.G. (Charles Greeley.Samuel Alfred Mitchell 1874-1960. National Academy of Sciences Biographical Memoir. Washington DC: National Academy of Sciences, 1962.
Available via NASOnline @ http://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/mitchell-samuel.pdf

Butler, Howard Russell. "An Ideal Astronomic Hall." Natural History, vol. XXVII, no. 4 (July-August 1926): 392-98.
Available @ https://digitallibrary.amnh.org/handle/2246/6349

Butler, Howard Russell. "Chapter XIV Painting the Solar Eclipse." Pages 162-178. Painter and Space; Or, The Third Dimension in Graphic Art. New York NY: Charles Scribner's Sons, 1923.
Available via Google Books @ https://books.google.com/books?id=AbRCAAAAYAAJ

Butler, Howard Russell. "Painting Eclipses and Lunar Landscapes." Natural History, vol. XXVI, no. 4 (July-August 1926): 356-362.
Available @ https://digitallibrary.amnh.org/handle/2246/6349

Butler, Howard Russell. "Painting the Solar Corona." Natural History, vol. XIX, no. 3 (March 1919): 264-271.
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/full/1921PMcCO...2..165M
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/pdf/1921PMcCO...2..165M

Family Search. "Herbert Bolivar Tschudy." FamilySearch.
Available @ https://ancestors.familysearch.org/en/KCXN-GK5/herbert-bolivar-tschudy-1874-1946

Hammond, John. "The Naval Observatory Eclipse Expedition, June 8, 1918." Popular Astronomy, vol. XXVII, no. 1, whole no. 261 (January 1919): 1-6.
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/full/1919PA.....27....1H
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/pdf/1919PA.....27....1H

Lawrence, Deirdre; Deborah Wythe; Laura Peimer; Ed McLoughlin; and Dr. Linda Ferber, consult. Guide to the Records of the Departments of European Painting and Sculpture, American Painting and Sculpture, Contemporary Art 1897-2005. Brooklyn NY: Brooklyn Museum.
Available @ https://d1lfxha3ugu3d4.cloudfront.net/archives/P&S_final.pdf

Lawrence, Jenny; and Richard Milner. "A Forgotten Cosmic Designer." Natural History, vol. CIX, no. 1 (February 2000): 100.
Available via Natural History Magazine @ https://www.naturalhistorymag.com/htmlsite/master.html?https://www.naturalhistorymag.com/htmlsite/features/0200_feature2.html

Marriner, Derdriu. "Saturday, June 8, 1918, Total Solar Eclipse Belongs to Saros Cycle 126." Earth and Space News. Wednesday, June 23, 2021.
Available @ https://earth-and-space-news.blogspot.com/2021/06/saturday-june-8-1918-total-solar.html

Marriner, Derdriu. "Total Solar Eclipse June 8, 1918, Was First of Two 1918 Solar Eclipses." Earth and Space News. Wednesday, June 16, 2021.
Available @ https://earth-and-space-news.blogspot.com/2021/06/total-solar-eclipse-june-8-1918-was.html

Mitchell, S.A. (Samuel Alfred). "The Total Solar Eclipse of 1918." Natural History, vol. XIX, no. 3 (March 1919): 244-263.
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/full/1921PMcCO...2..165M
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/pdf/1921PMcCO...2..165M

Time and Date. "June 8-9, 1918 Total Solar Eclipse." Time and Date > Sun & Moon > Eclipses.
Available @ https://www.timeanddate.com/eclipse/solar/1918-june-8

Time and Date. "June 8, 1918 -- Total Solar Eclipse -- Boulder, CO, USA." Time and Date > Sun & Moon > Eclipses.
Available @ https://www.timeanddate.com/eclipse/in/usa/boulder?iso=19180608

Tschudy, Herbert B. (Bolivar). "How the Eclipse Struck the Artist." The Brooklyn Museum Quarterly, vol. V, no. 3 (July 1918): 129-133.
Available via Internet Archive @ https://archive.org/details/brooklynmuseumqu46broouoft/page/n409/mode/1up?view=theater

Wednesday, June 23, 2021

Saturday, June 8, 1918, Total Solar Eclipse Belongs to Saros Cycle 126

Summary: The Saturday, June 8, 1918, total solar eclipse belongs to Saros cycle 126, a family of 72 similar solar eclipses.

The Saturday, June 8, 1918, total solar eclipse belongs to Saros cycle 126, which comprises 72 solar eclipses exhibiting similar geometries.

The solar Saros cycle groups solar eclipses with similar geometries into families, known as series. For example, all solar eclipses in a particular Saros series occur at the same lunar node. The two lunar nodes, known as ascending and descending, indicates the two intersections of the lunar orbit with Earth's orbit. The ascending node signals lunar passage to the north of Earth's orbit. The descending node marks passage to the south of Earth's orbit.

All solar Saros series 126 eclipses occur at the descending node. Consequently, each succeeding eclipse in the series attests to the moon's northward movement away from the node.

A Saros cycle's duration approximates 6,585.3 days (18 years 11 days 8 hours). Specifically, Saros series 126 lasts for 1,280.14 years, according to NASA (National Aeronautics and Space Administration) Eclipse Web Site's eclipse predictions by NASA astrophysicist, now retired, Fred Espenak. Saros series 126 spans 14 centuries, from the 12th to the 25th centuries.

Saros series 126 comprises 31 partial solar eclipses, 28 annular solar eclipses, three hybrid solar eclipses and 10 total solar eclipses. The cycle's 72 eclipses sequence as five sets. The first set comprises eight partial solar eclipses. The second set contains 28 annular solar eclipses. The third set is composed of three hybrid solar eclipses. The fourth set features 10 total solar eclipses. The cycle's fifth and last set contains the last 23 of the cycle's 31 partial solar eclipses.

Saros series 126 opened March 10, 1179, with a partial solar eclipse. The series will close with a partial solar eclipse on Saturday, May 3, 2459. As exemplars of Saros series 126's northward movement from the descending lunar node, the opening eclipse was a Southern Hemisphere phenomenon, while the closing eclipse will favor Earth's Northern Hemisphere.

The Saturday, June 8, 1918, total solar eclipse appeared as 42nd in the Saros series 126 lineup of 72 eclipses. The June 1918 event numbered as third in the cycle's set of 10 total solar eclipses.

The June 1918 total solar eclipse's predecessor was the total solar eclipse of Monday, May 28, 1900. The May 1900 total solar eclipse occurred as second in the cycle's set of 10 total solar eclipses and as 41st in Saros series 126's overall lineup of 72 eclipses.

The June 1918 total solar eclipse's successor was the total solar eclipse of Friday, June 19, 1936. The June 1936 total solar eclipse appeared as fourth in the cycle's 10-member set of total solar eclipses and as 43rd in the cycle's overall 72-member lineup.

The Saros series 126's set of 10 total solar eclipses covers two centuries, spanning the 19th through 21st centuries. The set's opening total solar eclipse, which took place Wednesday, May 17, 1882, numbered as 40th in Saros series 126's overall lineup of 72 eclipses. The total solar eclipse of Tuesday, Aug. 23, 2044, will conclude the set as Saros series 126's 10th and last total solar eclipse. The August 2044 total solar eclipse will appear as 49th in Saros series 126's overall lineup of 72 eclipses.

The extreme durations predicted by Fred Espenak on the NASA Eclipse Web Site recognize the Monday, July 10, 1972, total solar eclipse's duration of 2 minutes 36 seconds as Saros series 126's longest total solar eclipse. The July 1972 total solar eclipse numbered as the set's sixth member and as 45th in Saros series 126's overall lineup of 72 eclipses. With a duration of only 1 minute 50 seconds, the total solar eclipse set's opening eclipse, Wednesday, May 17, 1882, qualifies as the shortest total solar eclipse.

The takeaways for the Saturday, June 8, 1918, total solar eclipse belonging to Saros series 126 are that the event occurred as third in Saros series 126's set of 10 total solar eclipses; that the June 1918 total solar eclipse numbered as 42nd in the Saros series 126 lineup of 72 eclipses; that the June 1918 total solar eclipse's predecessor was the Monday, May 28, 1900, total solar eclipse; and that the June 1918 total solar eclipse's successor was the Friday, June 19, 1936, total solar eclipse.

Acknowledgment

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

Image credits:

A partial eclipse on March 10, 1179, opened solar Saros series 126's lineup of 72 similar eclipses: "Permission is freely granted to reproduce this data when accompanied by an acknowledgment: Eclipse Predictions by Fred Espenak (NASA's GSFC)", via NASA Eclipse Web Site (https://eclipse.gsfc.nasa.gov/SEpubs/copyright.html) @ https://eclipse.gsfc.nasa.gov/5MCSEmap/1101-1200/1179-03-10.gif

A partial eclipse on Saturday, May 3, 2459, will close solar Saros series 126's lineup of 72 similar eclipses: "Permission is freely granted to reproduce this data when accompanied by an acknowledgment: Eclipse Predictions by Fred Espenak (NASA's GSFC)", via NASA Eclipse Web Site (https://eclipse.gsfc.nasa.gov/SEpubs/copyright.html) @ https://eclipse.gsfc.nasa.gov/5MCSEmap/2401-2500/2459-05-03.gif

For further information:

Espenak, Fred. "Partial 1179 Mar 10." NASA Eclipse Web Site > Solar Eclipses > Solar Eclipse Catalogs > Saros Catalog of Solar Eclipses: Saros 0 to 180 > Summary of Saros Series 125 to 150.
Available @ https://eclipse.gsfc.nasa.gov/5MCSEmap/1101-1200/1179-03-10.gif

Espenak, Fred. "Partial 2459 May 03." NASA Eclipse Web Site > Solar Eclipses > Solar Eclipse Catalogs > Saros Catalog of Solar Eclipses: Saros 0 to 180 > Summary of Saros Series 125 to 150.
Available @ https://eclipse.gsfc.nasa.gov/5MCSEmap/2401-2500/2459-05-03.gif

Espenak, Fred. "Saros Series 126." EclipseWise > Solar Eclipses > Solar Eclipse Links > Catalog of Solar Eclipse Saros Series > Saros -33 to 190 > Summary of Saros 117 to 146.
Available @ http://www.eclipsewise.com/solar/SEsaros/SEsaros126.html

Espenak, Fred. "Saros Series 126." NASA Eclipse Web Site > Solar Eclipses > Solar Eclipse Catalogs > Saros Catalog of Solar Eclipses: Saros 0 to 180 > Summary of Saros Series 125 to 150.
Available @ https://eclipse.gsfc.nasa.gov/SEsaros/SEsaros126.html

Espenak, Fred. "Total 1882 May 17." NASA Eclipse Web Site > Solar Eclipses > Solar Eclipse Catalogs > Saros Catalog of Solar Eclipses: Saros 0 to 180 > Summary of Saros Series 125 to 150.
Available @ https://eclipse.gsfc.nasa.gov/5MCSEmap/1801-1900/1882-05-17.gif

Espenak, Fred. "Total 1900 May 28." NASA Eclipse Web Site > Solar Eclipses > Solar Eclipse Catalogs > Saros Catalog of Solar Eclipses: Saros 0 to 180 > Summary of Saros Series 125 to 150.
Available @ https://eclipse.gsfc.nasa.gov/5MCSEmap/1801-1900/1900-05-28.gif

Espenak, Fred. "Total 1936 Jun 19." NASA Eclipse Web Site > Solar Eclipses > Solar Eclipse Catalogs > Saros Catalog of Solar Eclipses: Saros 0 to 180 > Summary of Saros Series 125 to 150.
Available @ https://eclipse.gsfc.nasa.gov/5MCSEmap/1901-2000/1936-06-19.gif

Espenak, Fred. "Total 1972 Jul 10." NASA Eclipse Web Site > Solar Eclipses > Solar Eclipse Catalogs > Saros Catalog of Solar Eclipses: Saros 0 to 180 > Summary of Saros Series 125 to 150.
Available @ https://eclipse.gsfc.nasa.gov/5MCSEmap/1901-2000/1972-07-10.gif

Espenak, Fred. "Total 2044 Aug 23." NASA Eclipse Web Site > Solar Eclipses > Solar Eclipse Catalogs > Saros Catalog of Solar Eclipses: Saros 0 to 180 > Summary of Saros Series 125 to 150.
Available @ https://eclipse.gsfc.nasa.gov/5MCSEmap/2001-2100/2044-08-23.gif

Espenak, Fred. "Total Solar Eclipse of 1918 Jun 08." EclipseWise > Solar Eclipses > Solar Eclipse Links > Decade Pages of Solar Eclipses > Solar Eclipses: 1911-1920.
Available @ http://www.eclipsewise.com/solar/SEprime/1901-2000/SE1918Jun08Tprime.html

Espenak, Fred. "Total Solar Eclipse of 1918 Jun 08." NASA Eclipse Web Site > Solar Eclipses > Decade Tables of Solar Eclipses > Solar Eclipses: 1911-1920.
Available @ https://eclipse.gsfc.nasa.gov/SEplot/SEplot1901/SE1918Jun08T.GIF

Wednesday, June 16, 2021

Total Solar Eclipse June 8, 1918, Was First of Two 1918 Solar Eclipses

Summary: The total solar eclipse June 8, 1918, was first of two 1918 solar eclipses, was a Northern Hemisphere event and was first in lineup of five eclipses.

The total solar eclipse June 8, 1918, was the first of two 1918 solar eclipses, was a Northern Hemisphere event and was also the first in the year's lineup of three lunar and two solar eclipses, of which the second solar eclipse was annular.

The June 1918 solar eclipse favored the Northern Hemisphere. The path of totality tracked, from its touchdown south of Japan, westward across the North Pacific Ocean; slanted across the United States from the Pacific Northwest to the South East's Florida; and then skimmed the North Atlantic Ocean for liftoff at the then-British crown colony of the Bahamas (independent Commonwealth of the Bahamas since Tuesday, July 10, 1973), according to a contemporary account in the Journal of the Royal Astronomical Society of Canada by Robert Millford Motherwell (1882-Sept. 30, 1940) of Ottawa's Dominion Observatory.

The expansive availability of the June 1918 solar eclipse's partial component contrasted with the elite corridor of the June 1918 solar eclipse's total component. The path of partiality included the areas of North America that were excluded from the path totality and also stretched across northeastern Asia and northern Europe, according to retired NASA astrophysicist Fred Espenak's EclipseWise website. The Arctic sprawl across Earth's upper northern latitudes also experienced the path of partiality, according to the Time and Date website.

Espenak's EclipseWise website also places the sun in Taurus the Bull constellation during the Saturday, June 8, 1918, solar eclipse and notes that lunar perigee preceded the event by 3.6 days. Lunar perigee (Ancient Greek: περί, perí, “near” + γῆ, gê, “Earth”) took place Wednesday, June 5 at 7:48 Coordinated Universal Time (3:48 a.m. Eastern Daylight Time), at a distance of 366,911 kilometers, according to computer programmer John Walker's Fourmilab Switzerland website.

The instant of first external contact between the lunar penumbra (shadow's lighter, outer region) and Earth's limb, designated as P1, initiates a partial solar eclipse. This first external penumbral contact took place Saturday, June 8, 1918, at 19:28:49.8 Universal Time (3:28 p.m. Eastern Daylight Time).

The instant of first external contact between the lunar umbra (shadow's dark center) and Earth's limb, designated as U1, starts a total eclipse. This first external umbral contact occurred at 20:31:31.4 UT (4:31 p.m. EDT).

Totality references a total eclipse's maximum phase, characterized by complete coverage of the solar disk by the lunar disk. Totality spans the first and last internal contacts of the lunar umbra with Earth's limb.

The instant of first internal contact between the umbra and Earth's limb, designated as U2, took place at 20:32:28.6 UT (4:32 p.m. EDT). This first internal umbral contact actually sequences as the second contact overall, as it is preceded by the first external umbral contact (U1).

Greatest eclipse defines as the instant of closest passage of the lunar shadow cone's axis to Earth's center. The Saturday, June 8, 1918, total solar eclipse's greatest eclipse happened at 22:07:22.9 UT (6:07 p.m. EDT).

Greatest eclipse occurred in the North Pacific Ocean, south of Alaska's Kodiak Island, at 50 degrees 50.9 minutes north latitude, 152 degrees 01.6 minutes west longitude. The path of totality at greatest eclipse had a width of 112.0 kilometers. The duration at greatest eclipse was 2 minutes 22.8 seconds.

The moon's geocentric coordinates at greatest eclipse were right ascension of 5 hours 4 minutes 40.4 seconds and declination of plus 23 degrees 17 arcminutes 39.0 arcseconds. The sun's geocentric coordinates were right ascension of 5 hours 4 minutes 40.0 seconds and declination of plus 22 degrees 50 arcminutes 23.8 arcseconds.

The instant of last internal contact between the umbra and Earth's limb, designated as U3, occurred at 23:42:20.2 UT (7:42 p.m. EDT). This last internal umbral contact sequences as the second and last internal umbral contact and as the third of the four contacts (two internal, two external) overall between the umbra and Earth's limb.

A total eclipse terminates at the instant of last external contact between the umbra and Earth's limb, designated as U4. This last external umbral contact numbers as the fourth and last of the four contacts overall between the umbra and Earth's limb. The Saturday, June 8, 1918, total solar eclipse ended at 23:43:12.3 UT (7:43 p.m. EDT).

The instant of last external contact of the lunar penumbra with Earth's limb closes a partial eclipse. For the Monday, June 8, 1918, solar eclipse, this last external penumbral contact occurred Tuesday, June 9, at 00:46:01.4 UT (Monday, June 8, at 8:46 p.m. EDT).

The June 1918 solar event's partial eclipse lasted for 5 hours 17 minutes 11.6 seconds. The June 1918 solar event's total eclipse had a duration of 3 hours 11 minutes 40.9 seconds.

The first photoelectric measurements of a total solar eclipse numbered among the achievements associated with contemporary scientific study of the Saturday, June 8, 1918, total solar eclipse, according to the University of Illinois at Urbana-Champaign's Sesquicentennial 1867-2017 Celebration website. American astronomer and University of Illinois at Urbana Observatory director Joel Stebbins (July 30, 1878-March 16, 1966) and Swiss-born American-naturalized University of Illinois theoretical physicist Jakob Kunz (Nov. 3, 1874-July 18, 1938) made the measurements as leaders of the Illinois Eclipse Expedition to Rock Springs, Wyoming.

The Saturday, June 8, 1918, total solar eclipse occurred as the first of 1918's two solar eclipses. The year's second solar eclipse took place Tuesday, Dec. 3, as an annular solar eclipse.

The takeaways for the June 8, 1918, total solar eclipse are that it was the first of two 1918 solar eclipses; that the path of totality favored the continental United States; that the eclipse occasioned the first photoelectric measurements of a total solar eclipse; that the photoelectric measurements were made by American astronomer Joel Stebbins and Swiss-born American-naturalized theoretical physicist Jakob Kunz; and that the year's second solar eclipse occurred almost six months later as an annular solar eclipse.

animated path of Saturday, June 8, 1918, total solar eclipse: Aug. 23, 2017: Tomruen, CC BY SA 4.0 International, via Wikimedia Commons

Acknowledgment

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

Image credits:

Saturday, June 8, 1918, total solar eclipse details: "Permission is freely granted to reproduce this data when accompanied by an acknowledgment: Eclipse Predictions by Fred Espenak, NASA's GSFC," via NASA Eclipse Web Site (https://eclipse.gsfc.nasa.gov/SEpubs/copyright.html) @ https://eclipse.gsfc.nasa.gov/SEplot/SEplot1901/SE1918Jun08T.GIF

animated path of Saturday, June 8, 1918, total solar eclipse: Aug. 23, 2017: Tomruen, CC BY SA 4.0 International, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Solar_eclipse_of_1918_June_8_animated_globe.gif

For further information:

Aldrich, L.B. (Loyal Blaine). The Smithsonian Eclipse Expedition of June 8, 1918. Smithsonian Miscellaneous Collections, vol. 69 no. 9. Publication 2527. Washington DC: The Smithsonian Institution, Jan. 1, 1919.
Available via Internet Archive @ https://archive.org/details/smithsonianmisce691921smit/page/n864/mode/1up?view=theater

Butler, Howard Russell. "An Ideal Astronomic Hall." Natural History, vol. XXVII, no. 4 (July-August 1926): 392-98.
Available @ https://digitallibrary.amnh.org/handle/2246/6349

Butler, Howard Russell. "Painting Eclipses and Lunar Landscapes." Natural History, vol. XXVI, no. 4 (July-August 1926): 356-362.
Available @ https://digitallibrary.amnh.org/handle/2246/6349

Espenak, Fred. "Explanation of Solar Eclipse Predictions." NASA Eclipse Web Site.
Available @ https://eclipse.gsfc.nasa.gov/SEmono/reference/explain.html

Espenak, Fred. "Glossary of Solar Eclipse Terms." NASA Eclipse Web Site.
Available @ https://eclipse.gsfc.nasa.gov/SEhelp/SEglossary.html

Espenak, Fred. "Key to Solar Eclipse Global Maps." NASA Eclipse Web Site.
Available @ https://eclipse.gsfc.nasa.gov/OH/SEplotkey.html

Espenak, Fred. "Path of the Total Solar Eclipse of 1918 Jun 08." NASA Eclipse Web Site > Solar Eclipses > Saros Catalog of Solar Eclipses: Saros 0-180 > Saros Series Catalog of Solar Eclipses > Catalog of Solar Eclipses of Saros 126 > Central Dur.
Available @ https://eclipse.gsfc.nasa.gov/SEpath/SEpath1901/SE1918Jun08Tpath.html

Kunz, Jacob; and Joel Stebbins. "The Illinois Eclipse Expedition to Rock Springs Wyoming." Popular Astronomy, vol. XXVI, no. 10, whole no. 260 (December 1918): 665-675.
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/full/1918PA.....26..665S
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/pdf/1918PA.....26..665S

Kunz, Jacob; and Joel Stebbins. "A Photo-Electric Determination of the Brightness of the Corona at the Eclipse of June 8, 1918." Astrophysical Journal, vol. XLIX, no. 3 (April 1919): 137-152. Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/full/1919ApJ....49..137K
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/pdf/1919ApJ....49..137K

Marriner, Derdriu. "Total Lunar Eclipse Feb. 9, 1906, Was First of Two 1906 Lunar Eclipses." Earth and Space News. Wednesday, Feb. 3, 2021.
Available @ https://earth-and-space-news.blogspot.com/2021/02/total-lunar-eclipse-feb-9-1906-was.html

McDiarmid, R.J. "Robert Millford Motherwell, 1882-1940." The Journal of the Royal Astronomical Society of Canada, vol. XXXIV, no. 10, whole no. 299 (December 1940): 441-443.
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/full/1940JRASC..34..441M
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/pdf/1940JRASC..34..441M

Mitchell, S.A. (Samuel Alfred). "Personal Experiences at Eclipse Expeditions: With a Supplement in Color of the Three Solar Eclipses Seen in the United States in 1918, 1923, and 1925." Natural History, vol. XXVII, no. 4 (July-August 1926): 344-355.
Available @ https://digitallibrary.amnh.org/handle/2246/6349
Available @ https://www.naturalhistorymag.com/htmlsite/master.html?https://www.naturalhistorymag.com/htmlsite/editors_pick/1926_07-08_pick.html

Mitchell, Samuel Alfred. Eclipses of the Sun. New York NY: Columbia University, 1923.

Motherwell, R.M. "The Total Solar Eclipse, June 8, 1918." Journal of the Royal Astronomical Society of Canada, vol. XII, no. 4 (April 1918):160-168.
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://articles.adsabs.harvard.edu/full/1918JRASC..12..160M
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://articles.adsabs.harvard.edu/pdf/1918JRASC..12..160M
Available via HathiTrust @ https://hdl.handle.net/2027/uc1.b2924694?urlappend=%3Bseq=174

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Time and Date. "Solar and Lunar Eclipses Worldwide -- 1918." Time and Date > Sun & Moon > Eclipses.
Available @ https://www.timeanddate.com/eclipse/1918

University of Illinois at Urbana-Champaign. "June 8, 1918 Astronomer Joel Stebbins and physicist Jacob Kunz make the first photoelectric measurements of a total solar eclipse." Illinois 150 > Timeline.
Available @ http://150.illinois.edu/timeline-details#81

Walker, John. "Lunar Perigee and Apogee Calculator." Fourmilab Switzerland > Earth and Moon Viewer and Solar System Explorer.
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Wilson, H.C. (Herbert Couper). "The Total Eclipse of the Sun June 8, 1918." Popular Astronomy, vol. XXVI, no. 5, whole no. 255 (May 1918):.
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/full/1918PA.....26..285W
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://adsabs.harvard.edu/pdf/1918PA.....26..285W