Solar eclipse of June 8, 1918


A total solar eclipse occurred at the Moon's descending node of orbit between Saturday, June 8 and Sunday, June 9, 1918, with a magnitude of 1.0292. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. Occurring 3.7 days after perigee, the Moon's apparent diameter was larger.
The eclipse was viewable across the entire contiguous United States, an event which would not occur again until the solar eclipse of August 21, 2017.

The Path

The path of totality started south of Japan, went across the Pacific Ocean, passing northern part of Kitadaitō, Okinawa and the whole Tori-shima in Izu Islands on June 9, and then acrossed the contiguous United States and British Bahamas on June 8. The largest city to see totality was Denver, although many could theoretically see it as the size of the shadow was between across as it traveled across America. The longest duration of totality was in the Pacific at a point south of Alaska. The path of the eclipse finished near Bermuda.
Besides the path where a total solar eclipse was visible, a partial solar eclipse was visible in the eastern part of East Asia, northern part of Northern Europe, eastern part of Micronesia, Hawaii Islands, northeastern Russian Empire, the entire North America except the Lesser Antilles, and the northwestern tip of South America.

U.S. Observation team

The path of the eclipse clipped Washington state, and then moved across the whole of Oregon through the rest of the country, exiting over Florida. The U.S. Naval Observatory obtained a special grant of $3,500 from Congress for a team to observe the eclipse in Baker City, Oregon. The team had been making preparations since the year before, and John C. Hammond led the first members to Baker City on April 11. The location was important, as it influenced the probability of cloud cover and the duration and angle of the sun during the eclipse. The team included Samuel Alfred Mitchell as its expert on eclipses, and Howard Russell Butler, an artist and physicist. In a time before reliable colour photography, Butler's role was to paint the eclipse at totality after observing it for 112.1 seconds. He noted later that he used a system of taking notes of the colours using skills he had learned for transient effects.
Joel Stebbins and Jakob Kunz from the University of Illinois Observatory made the first photoelectric photometric observations of the solar corona from their observing site near Rock Springs, Wyoming

Observation

As the total eclipse approached, the team watched as clouds obscured the Sun. The clouds did clear, but during their most important observations the Sun was covered by a thin cloud; the Sun was completely visible five minutes later. This was not unusual, as cloudy conditions were reported across the country, where the eclipse was also observed from the Yerkes Observatory, Lick Observatory, and Mount Wilson Observatory.
Following the 1915 prediction of Albert Einstein's General theory of relativity that light would be deflected when passing near a massive object such as the Sun, the USNO expedition attempted to validate Einstein's prediction by measuring the position of stars near the Sun. The cloud cover during totality obscured observations of stars, though, preventing this test of the validity of general relativity from being completed until the solar eclipse of May 29, 1919.

Eclipse details

Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the Moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.
EventTime
First Penumbral External Contact1918 June 8 at 19:29:10.1 UTC
First Umbral External Contact1918 June 8 at 20:31:51.8 UTC
First Central Line1918 June 8 at 20:32:20.5 UTC
First Umbral Internal Contact1918 June 8 at 20:32:49.1 UTC
Ecliptic Conjunction1918 June 8 at 22:02:46.3 UTC
Greatest Duration1918 June 8 at 22:05:43.3 UTC
Equatorial Conjunction1918 June 8 at 22:07:34.5 UTC
Greatest Eclipse1918 June 8 at 22:07:43.2 UTC
Last Umbral Internal Contact1918 June 8 at 23:42:40.5 UTC
Last Central Line1918 June 8 at 23:43:06.6 UTC
Last Umbral External Contact1918 June 8 at 23:43:32.6 UTC
Last Penumbral External Contact1918 June 9 at 00:46:21.9 UTC

ParameterValue
Eclipse Magnitude1.02920
Eclipse Obscuration1.05925
Gamma0.46582
Sun Right Ascension05h04m40.0s
Sun Declination+22°50'23.8"
Sun Semi-Diameter15'45.3"
Sun Equatorial Horizontal Parallax08.7"
Moon Right Ascension05h04m40.4s
Moon Declination+23°17'39.1"
Moon Semi-Diameter15'59.0"
Moon Equatorial Horizontal Parallax0°58'39.4"
ΔT20.5 s

Eclipse season

This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months 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.
June 8
Descending node 		June 24
Ascending node
Total solar eclipse
Solar Saros 126		Partial lunar eclipse
Lunar Saros 138

Related eclipses

Eclipses in 1918

A total solar eclipse on June 8.

Metonic

Tzolkinex

Half-Saros

Tritos

Solar Saros 126

Inex

Triad

Other links