Partial Solar Eclipse July 13 Is Second of Three 2018 Solar Eclipses

Summary: The partial solar eclipse July 13 is the second of three 2018 solar eclipses, with all three occurring as partial eclipses for Earth’s observers.

graphics and details of Friday, July 13, 2018, partial solar eclipse: "Permission is freely granted to reproduce this data when accompanied by an acknowledgment, Eclipse Predictions by Fred Espenak, NASA GSFC Emeritus," via NASA Eclipse Web Site

The partial solar eclipse July 13 is the second of three 2018 solar eclipses, with all three happening as partial eclipses, as viewed from Earth.

The partial solar eclipse Friday, July 13, 2018, is an event observable in a small section of the Southern Hemisphere. The year’s second partial solar eclipse favors oceanic over continental locations. July’s partial solar eclipse begins over the southeasternmost Indian Ocean and ends over the southwesternmost South Pacific Ocean. The eclipse’s oceanic visibility region takes in Antarctica’s Southern Ocean and the Bass Strait, which separates Australia’s southern state of Victoria from the Australian island state of Tasmania.

Continental viewing of the partial solar eclipse favors small portions of northern Antarctica and southeastern Australia. July’s solar event affords visibility to the southernmost slice of the Land Down Under’s south central state of South Australia and to most of the southeastern state of Victoria.

The solar event’s insular visibility region encompasses Australia’s southernmost state, the island of Tasmania. Also, New Zealand claims visibility by way of the southwest Pacific island country’s third largest island. Stewart Island lies about 30 kilometers (19 miles) south of New Zealand’s largest island, South Island.

July’s partial solar eclipse begins with first contact between Earth’s surface and the lunar penumbra, the lighter, outer region of the moon’s shadow. First contact takes place Friday, July 13, at 01:48:17.5 Universal Time (11:18 a.m. Australian Central Standard Time; 11:48 a.m. Australian Eastern Standard Time; 1:48 p.m. New Zealand Standard Time), according to (now retired) NASA astrophysicist Fred Espenak on NASA’s Eclipse Website.

Greatest eclipse is expected over northern Antarctica at 03:01:07.0 UT1 (12:31 p.m. ACST; 1:01 p.m. AEST; 3:01 p.m. NZST). For solar eclipses, greatest eclipse (GE) references the instant of closest passage by the lunar shadow cone’s axis to Earth’s center.

Last contact before Earth’s exit from the lunar penumbra signals the end of July’s partial solar eclipse. Last contact occurs at 04:13:46.8 UT1 (1:43 p.m. ACST; 2:13 p.m. AEST; 3:03 p.m. NZST).

July’s solar eclipse occurs as the second of three 2018 partial solar eclipses. The year’s first solar eclipse took place Thursday, Feb. 15. The year’s third and last partial solar eclipse happens Saturday, Aug. 11.

July’s solar eclipse joins January’s solar eclipse in affording visibility only in Earth’s Southern Hemisphere. The year’s third partial solar event, however, favors the Northern Hemisphere.

The year’s second solar eclipse shares occurrence in July with 2018’s second and last lunar eclipse. The total lunar eclipse Friday, July 27, takes place about two weeks after the month’s solar eclipse.

A partial solar eclipse occurs as the natural phenomenon of partial eclipsing, or obscuring, of the sun by the moon. The casting of only the lighter, outer region of the moon’s shadow ensues from a lack of straight line alignment of sun, moon and Earth.

July’s partial solar eclipse begins 6 hours 39 minutes before the moon reaches monthly perigee, or closest center-to-center distance between Earth and moon. Retired NASA astrophysicist Fred Espenak’s Astro Pixels’ website places the instant of the month’s perigee Friday, July 13, at 08:28 a.m. Greenwich Mean Time/Coordinated Universal Time (4:28 a.m. Eastern Daylight Time; 5:58 p.m. ACST; 6:28 p.m. AEST; 8:28 p.m. NZST). Perigee marked a center-to-center distance of 357,432 kilometers (about 222,098 miles).

July’s partial solar eclipse claims the closest moon-Earth distance of the year’s five eclipses. July’s perigee was also the year’s second closest perigee. Minimum, or closest, perigee occurred Monday, Jan. 1, at 21:54 UT, at 356,566 kilometers (about 221,560 miles). January’s perigee of 356,566 kilometers was 866 kilometers closer to Earth than July’s perigee of 357,432 kilometers.

July’s lunar eclipse claims the farthest moon-Earth distance of the year’s five eclipses. The Friday, July 27, total lunar eclipse logged a center-to-center moon-Earth distance of 406,223 kilometers. The July lunar eclipse’s distance was also the year’s second farthest moon-Earth distance. The year’s apogee, or farthest distance, occurred Monday, Jan. 15, at 406,461 kilometers (about 252,563 miles).

July’s partial solar eclipse belongs to Saros cycle 117. The Saros cycle assigns similar eclipses to families, known as series. A Saros cycle approximates 6,585.3 days (18 years 11 days 8 hours). Eclipses in the same Saros cycle share similar geometries, such as occurrence at the same ascending or descending node, with nearly the same lunar distance from Earth.

The two nodes of significance in the Saros cycle are the two points where the moon’s orbit crosses the Earth’s orbit. The two points register the approximately 5.1-degree tip of the moon’s orbit to the Earth’s orbit around the sun.

The ascending node associates with the lunar crossing to the north of Earth’s orbit. The descending node concerns the moon’s passage to the south.

Saros 117 eclipses occur at the moon’s ascending node. The moon exhibits a southward movement with each eclipse.

The takeaways for the partial solar eclipse July 13, 2018, are that it occurs as the second of the year’s three partial solar eclipse, shares July with 2018’s second lunar eclipse and claims the closest moon-Earth distance of 2018’s five eclipses.

animation of partial solar eclipse Friday, July 13, 2018: A.T. Sinclair/NASA, Public Domain, 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:

graphics and details of Friday, July 13, 2018, partial solar eclipse: "Permission is freely granted to reproduce this data when accompanied by an acknowledgment, Eclipse Predictions by Fred Espenak, NASA GSFC Emeritus," via NASA Eclipse Web Site @ https://eclipses.gsfc.nasa.gov/SEplot/SEplot2001/SE2018Jul13P.GIF

animation of partial solar eclipse Friday, July 13, 2018: A.T. Sinclair/NASA, Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:SE2018Jul13P.gif

For further information:

“Accuracy of Eclipse Times.” TimeAndDate > Sun & Moon > Eclipses.
Available @ https://www.timeanddate.com/eclipse/accuracy.html

Espenak, Fred. “Eclipses During 2018.” EclipseWise > Solar Eclipses > Eclipses During 2018.
Available @ http://www.eclipsewise.com/oh/ec2018.html

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

Espenak, Fred. “Key to Catalog of Solar Eclipses.” EclipseWise.
Available @ https://www.eclipsewise.com/solar/SEhelp/SEsarcatkey.html

Espenak, Fred. “Moon at Perigee and Apogee: 2001 to 2100 Greenwich Mean Time.” Astro Pixels > Ephemeris > Moon.
Available @ http://astropixels.com/ephemeris/moon/moonperap2001.html

Espenak, Fred. “Partial Solar Eclipse of 2018 Feb 15.” EclipseWise > Solar Eclipses > Eclipses During 2018 > Partial Solar Eclipse of February 15.
Available @ https://www.eclipsewise.com/oh/oh-figures/ec2018-Fig02.pdf

Espenak, Fred. “Partial Solar Eclipse of 2018 Jul 13.” NASA Eclipse Web Site > Solar Eclipses > Decade Tables of Solar Eclipses  > Solar Eclipses : 2011-2020.
Available @ https://eclipses.gsfc.nasa.gov/SEplot/SEplot2001/SE2018Jul13P.GIF

Espenak, Fred. “Partial Solar Eclipse of 2018 Jul 13.” EclipseWise > Lunar Eclipses > Eclipses During 2018.
Available @ http://www.eclipsewise.com/oh/oh-figures/ec2018-Fig03.pdf

Espenak, Fred. “Saros 117.” EclipseWise > Solar Eclipses > Saros Catalog of Solar Eclipses.
Available @ http://www.eclipsewise.com/solar/SEsaros/SEsaros117.html

“July 13, 2018 -- Partial Solar Eclipse.” TimeAndDate > Sun & Moon > Eclipses.
Available @ https://www.timeanddate.com/eclipse/solar/2018-july-13

Marriner, Derdriu. "Crater Timings for Jan. 31, 2018, Total Lunar Eclipse Show Umbral Span." Earth and Space News. Wednesday, Jan. 17, 2018.
Available @ https://earth-and-space-news.blogspot.com/2018/01/crater-timings-for-jan-31-2018-total.html

Marriner, Derdriu. "First 2018 Eclipse Is Blue Moon Total Lunar Eclipse Wednesday, Jan. 31." Earth and Space News. Wednesday, Jan. 24, 2018.
Available @ https://earth-and-space-news.blogspot.com/2018/01/first-2018-eclipse-is-blue-moon-total.html

Marriner, Derdriu. "Jan. 31, 2018, Blue Moon Total Lunar Eclipse Belongs to Saros Cycle 124." Earth and Space News. Wednesday, Jan. 10, 2018.
Available @ https://earth-and-space-news.blogspot.com/2018/01/jan-31-2018-blue-moon-total-lunar.html

Marriner, Derdriu. “Partial Solar Eclipse Feb. 15 Is First of Three 2018 Solar Eclipses.” Earth and Space News. Wednesday, Feb. 7, 2018.
Available @ https://earth-and-space-news.blogspot.com/2018/02/partial-solar-eclipse-feb-15-is-first.html

McClure, Bruce. “Possible to Have 3 Eclipses in 1 Month?” EarthSky > Astronomy Essentials > Space. July 10, 2018.
Available @ http://earthsky.org/?p=183093

“Universal Time.” U.S. Naval Observatory > Astronomical Information Center > Time.
Available @ http://aa.usno.navy.mil/faq/docs/UT.php