Super Blue Moon Wednesday, Jan. 31, Is First of Two 2018 Blue Moons

Summary: The super blue moon Wednesday, Jan. 31, is the first of two 2018 blue moons, with blue designating the second of two full moons within one calendar month.

night side of moon at instant of reaching super blue fullness, Wednesday, Jan. 31, at 13:27 UTC: John Walker via Fourmilab

The super blue moon Wednesday, Jan. 31, is the first of two 2018 blue moons, with the blue designation applying to the second of two full moons that occur within the same calendar month.

January 2018’s first blue moon turns full Wednesday, Jan. 31, at 13:27 Coordinated Universal Time (8:27 a.m. Eastern Standard Time; 6:27 a.m. Pacific Standard Time). Almost two months later (58 days 23 hours 10 minutes), the year’s second blue moon reaches fullness Saturday, March 31, at 12:37 UTC (8:37 a.m. Eastern Daylight Time; 5:37 a.m. Pacific Daylight Time).

The year’s first blue moon claims triple honors. In addition to blue moon status, January 2018’s second full moon is a supermoon and also hosts a total lunar eclipse as 2018’s first of five eclipses.

Astrologer Richard Nolle is credited with coining the term of supermoon. Bruce McClure, EarthSky Tonight’s lead writer, explains Nolle’s definition as designating a new moon or full moon that logs a center-to-center distance of about 361,000 kilometers (224,000 miles) from Earth.

McClure places the Wednesday, Jan. 31, super blue moon at a center-to-center distance of 360,199 kilometers (223,817.28 miles). The blue moon’s distance is 1,204 kilometers farther away from Earth than January’s closest distance, known as perigee. The month’s perigee of 358,995 kilometers (223,069.15 miles) takes place 1 day 3 hours 33 minutes earlier, on Tuesday, Jan. 30, at 9:54 UTC (4:54 a.m. EST; 1:54 a.m. PST).

January’s super blue moon is the third in a series of three successive supermoon full moons. Its predecessors in the 2017-2018 supermoon trio reached supermoon fullness Sunday, Dec. 3, 2017, and Tuesday, Jan. 2, 2018. Of the trio, January 2018’s first full moon is the closest and largest. Its full moon distance, logged Jan. 2, at 2:24 UTC (Monday, Jan. 1, at 9:24 p.m. EST; 6:24 p.m. PST), is 356,846 kilometers (221,733.8 miles). Second place goes to December’s full moon supermoon, with a full moon distance of 357,987 kilometers (222,442.8 miles), logged Dec. 3 at 15:47 UTC (10:47 a.m. EST; 7:47 a.m. PST).

The year’s second blue moon, Saturday, March 31, is not a supermoon. AstroPixels, the astronomy-dedicated web site of retired NASA astrophysicist Fred Espenak, places the center-to-center distance between moon and Earth at 376,534 kilometers (miles) at the instant of March 2018 blue moon's fullness. Time and Date places the lunar distance at 376,498 (233,945 miles) from Earth’s center when the moon crosses Greenwich Borough’s meridian (zero degrees longitude) at 12:45 a.m. (Greenwich Mean Time; UTC). The Greenwich meridian passage happens eight minutes after 2018’s second blue moon reaches fullness at 12:37 GMT/UTC.

January’s blue moon also participates in 2018’s first eclipse, which begins at 10:51 UTC (12:51 a.m. Hawaii-Aleutian Standard Time). The super blue moon Wednesday, Jan. 31, is the first of two total lunar eclipses in 2018. The second total lunar eclipse takes place Friday, July 27.

January’s eclipse initiates 2018’s quintet of eclipses, which also includes three partial solar eclipses. The year’s solar eclipses occur Thursday, Feb. 15; Friday, July 13; Saturday, Aug. 11.

Contrastingly, 2018’s second blue moon only claims blue moon status. The Saturday, March 31, blue moon does not undergo an eclipse.

The most recent occurrence of two blue moons within the same calendar year in the 20th century (Jan. 1, 1901, to Dec. 31, 2000) happened in 1999. Blue moons happened Sunday, Jan. 31, at 16:07 UTC and Wednesday, March 31, at 22:49 UTC in 1999. January’s blue moon participated in a penumbral lunar eclipse that began at 16:17:31 UTC.

Three years feature two blue moons in the 21st century (Jan. 1, 2001, to Dec. 31, 2100). The immediate successor to 2018’s two blue moons is 2037. Blue moons will happen Saturday, Jan. 31, 14:04 UTC and Tuesday, March 31, at 09:53 UTC in 2037. January’s blue moon will participate in a total lunar eclipse that begins at 14:00:21 UTC.

The third instance of a year of two blue moons in the 21st century happens in 2094. The year’s first blue moon happens Sunday, Jan. 31, at 12:38 UTC. The second blue moon takes place Friday, April 30, at 13:55 UTC.

As the first of two 2018 blue moons, the super blue moon Wednesday, Jan. 31, offers a triple feature as a blue moon that undergoes a total lunar eclipse and has supermoon status.

Jan. 31, 2018, blue moon viewed from Earth at 13:27 UTC, instant of reaching fullness: John Walker via Fourmilab

Acknowledgment

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

Image credits:

night side of moon at instant of reaching super blue fullness, Wednesday, Jan. 31, at 13:27 UTC: John Walker via Fourmilab @ https://www.fourmilab.ch/cgi-bin/Earth

Jan. 31, 2018, blue moon viewed from Earth at 13:27 UTC, instant of reaching fullness: John Walker via Fourmilab @ https://www.fourmilab.ch/cgi-bin/Earth

For further information:

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