Solar eclipse of October 1, 1940

{{Infobox solar eclipse|1940Oct01

| previous = Solar eclipse of April 7, 1940

| next = Solar eclipse of March 27, 1941

}}

A total solar eclipse occurred at the Moon's ascending node of orbit on Tuesday, October 1, 1940,{{cite web|title=October 1, 1940 Total Solar Eclipse|url=https://www.timeanddate.com/eclipse/solar/1940-october-1|publisher=timeanddate|access-date=4 August 2024}} with a magnitude of 1.0645. 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 about 4 hours before perigee (on October 1, 1940, at 17:00 UTC), the Moon's apparent diameter was larger.{{cite web|title=Moon Distances for London, United Kingdom, England|url=https://www.timeanddate.com/astronomy/moon/distance.html?year=1940&n=136|publisher=timeanddate|access-date=4 August 2024}}

Totality was visible from Colombia, Brazil, Venezuela and South Africa. A partial eclipse was visible for parts of the Caribbean, South America, Central Africa, and Southern Africa.

Observation

Members of the Joint Permanent Eclipse Committee of the Royal Society and Royal Astronomical Society made observations in Brazil with interferometers and spectrometers. Teams of the Royal Observatory, Greenwich and Royal Observatory, Cape of Good Hope (now combined into the South African Astronomical Observatory) went to Calvinia, South Africa to study the gravitational lens proposed by the general relativity. Other scientists went to the edge of the path of totality to study the spectral lines of the solar chromosphere. A joint team of the Heliophysical Observatory of the University of Cambridge and the Radcliffe Observatory in Pretoria, South Africa (now combined into the South African Astronomical Observatory) went to Nelspoort to study the extreme ultraviolet spectrum of the chromosphere and corona, and conducted polarization studies of the corona and sky around the sun.{{cite journal|author=Stratton, F. J. M.|title=Total Solar Eclipse of October 1, 1940|journal=Nature|url=http://adsabs.harvard.edu/abs/1940Natur.145...32S|volume=145|issue=3662|page=32|year=1940|accessdate=2016-04-05|archive-date=27 August 2019|archive-url=https://web.archive.org/web/20190827223502/http://adsabs.harvard.edu/abs/1940Natur.145...32S}}

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.{{cite web|title=Total Solar Eclipse of 1940 Oct 01|url=https://eclipsewise.com/solar/SEprime/1901-2000/SE1940Oct01Tprime.html|publisher=EclipseWise.com|access-date=4 August 2024}}

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|+October 1, 1940 Solar Eclipse Times

! Event

! Time (UTC)

First Penumbral External Contact

| 1940 October 1 at 10:08:37.5 UTC

First Umbral External Contact

| 1940 October 1 at 11:03:28.3 UTC

First Central Line

| 1940 October 1 at 11:04:45.3 UTC

First Umbral Internal Contact

| 1940 October 1 at 11:06:02.4 UTC

First Penumbral Internal Contact

| 1940 October 1 at 12:04:11.7 UTC

Ecliptic Conjunction

| 1940 October 1 at 12:41:28.7 UTC

Greatest Eclipse

| 1940 October 1 at 12:44:06.1 UTC

Greatest Duration

| 1940 October 1 at 12:45:03.9 UTC

Equatorial Conjunction

| 1940 October 1 at 12:52:28.6 UTC

Last Penumbral Internal Contact

| 1940 October 1 at 13:23:47.3 UTC

Last Umbral Internal Contact

| 1940 October 1 at 14:22:03.5 UTC

Last Central Line

| 1940 October 1 at 14:23:20.8 UTC

Last Umbral External Contact

| 1940 October 1 at 14:24:38.0 UTC

Last Penumbral External Contact

| 1940 October 1 at 15:19:30.5 UTC

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|+October 1, 1940 Solar Eclipse Parameters

! Parameter

! Value

Eclipse Magnitude

| 1.06446

Eclipse Obscuration

| 1.13307

Gamma

| −0.25727

Sun Right Ascension

| 12h30m03.1s

Sun Declination

| -03°14'42.9"

Sun Semi-Diameter

| 15'58.8"

Sun Equatorial Horizontal Parallax

| 08.8"

Moon Right Ascension

| 12h29m44.0s

Moon Declination

| -03°29'44.3"

Moon Semi-Diameter

| 16'43.8"

Moon Equatorial Horizontal Parallax

| 1°01'24.1"

ΔT

| 24.7 s

Eclipse season

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.

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|+ Eclipse season of October 1940

! October 1
Ascending node (new moon) !! October 16
Descending node (full moon)

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| Total solar eclipse
Solar Saros 133

Penumbral lunar eclipse
Lunar Saros 145