October Hunter's Moon Is First or Second Full Moon Supermoon for 2016

Summary: Rating the October Hunter’s Moon as the first or second full moon supermoon for 2016 depends upon interpretation of a critical phrase in the supermoon definition.

albedo image of full moon supermoon at 04:23 UTC Oct. 16, 2016; view from 364,766 kilometers above 0 degrees north 0 degrees west: John Walker/Earth and Moon Viewer, Public Domain, via Fourmilab Switzerland

The October Hunter’s Moon status as the first or second full moon supermoon for 2016 depends upon the interpretation of supermoon as defined by astrologer Richard Nolle, who coined the term in an article for Dell Publishing Company’s Horoscope magazine in September 1979.

In an article for the October/November 2007 issue of the Mountain Astrologer, Richard Nolle shared the dictionary definition that he would envision for supermoon:
“A lunar perigee-syzygy, a New or Full Moon (syzygy) occurring when the Moon is at or near (within 90% of) its closest approach to Earth (perigee).”

Nolle lists three full moon supermoons for 2016 in the table of 21st century supermoons that he shares on his website, Astropro. The October Hunter’s Moon initiates three months of full moon supermoons, from October through December. Nolle identifies Dec. 3's full moon as the first and only full moon supermoon for 2017.

Retired NASA astrophysicist Fred Espenak, however, credits Friday, Sept. 16, as the first full moon supermoon for 2016. Espenak’s table identifies five-in-a-row full moon supermoons that fill autumn and winter 2016 and open 2017. Espenak identifies Thursday, Jan. 12, as the first full moon supermoon for 2017.

The difference between the two expert’s selection hinges upon the interpretation of the time frame for apogee, or farthest center-to-center distance from Earth, and perigee, or closest center-to-center approach to Earth. EarthSky lead writer Bruce McClure quotes Richard Nolle’s supermoon definition as “. . . a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth in a given orbit.”

McClure perceives Nolle’s list of 21st century full and new moon supermoons as based upon a distance that is 90 percent of the difference between the year’s closest perigee and farthest apogee. Farthest lunar distance for 2016 occurs Monday, Oct. 31, at 406,662 kilometers. On Monday, Nov. 14, two weeks later, closest approach occurs, at a distance of 356,509 kilometers. Ninety percent of the difference between apogee and perigee is 45,137.7 kilometers.

Subtracting the 90 percent figure from apogee yields 361,524.3 kilometers as the supermoon-defining distance for 2016. The September full moon’s distance, logged at 364,754 kilometers, exceeded the limiting distance for 2016.

Contrastingly, McClure explains Espenak’s supermoon table as based upon monthly calculations of apogee and perigee. The September full moon, known popularly as the year’s Harvest Moon, qualifies as a supermoon in relation to the month’s apogee and perigee. Subtracting September perigee at 361,896 kilometers from September apogee at 405,055 kilometers yields a difference of 43,159 kilometers.

The difference between apogee and full moon distance in September is 40,301 kilometers, which represents 93.378 percent of the difference between September’s apogee and perigee. McClure’s figures show that the September Harvest Moon fulfills the interpretation of the supermoon definition’s qualifying phrase, “in a given orbit,” as a monthly reference.

McClure points out that basing the limiting distance upon the year’s farthest apogee and closest perigee, in accordance with Nolle’s calculations, restricts the annual number of supermoons. Premising the limiting distance upon a given monthly orbit’s apogee and perigee, in accordance with Espenak’s figures, expands the annual number of supermoons.

The takeaway for the October Hunter’s Moon is that its supermoon status, whether as first or second full moon supermoon for 2016, is secure.

Blue Marble Monthlies map of day and night sides of Earth at instant of full moon supermoon’s turn to fullness, 04:23 UTC Oct. 16, 2016; Earth imagery from NASA Blue Marble Terra/MODIS cloudless Earth and Black Marble night lights images: John Walker/Earth and Moon Viewer, Public Domain, via Fourmilab Switzerland

Acknowledgment

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

Image credits:

albedo image of full moon supermoon at 04:23 UTC Oct. 16, 2016; view from 364,766 kilometers above 0 degrees north 0 degrees west: John Walker/Earth and Moon Viewer, Public Domain, via Fourmilab Switzerland @ https://www.fourmilab.ch/cgi-bin/Earth

Blue Marble Monthlies map of day and night sides of Earth at instant of full moon supermoon’s turn to fullness, 04:23 UTC Oct. 16, 2016; Earth imagery from NASA Blue Marble Terra/MODIS cloudless Earth and Black Marble night lights images: John Walker/Earth and Moon Viewer, Public Domain, via Fourmilab Switzerland @ https://www.fourmilab.ch/cgi-bin/Earth

For further information:

Espenak, Fred. “Astronomical Events in 2016.” EarthSky > Astronomy Essentials > Science Wire > Space. May 3, 2016.
Available @ http://earthsky.org/space/astronomical-phenomena-events-for-this-year

Espenak, Fred. “Full Moon at Perigee (Super Moon): 2001 to 2100 Greenwich Mean Time.” Astro Pixels > Ephemeris > Moon.
Available @ http://astropixels.com/ephemeris/moon/fullperigee2001.html

Marriner, Derdriu. "Aug. 29 Supermoon Kicks Off Three Months of Supersized Full Moons." Earth and Space News. Saturday, Aug. 29, 2015.
Available @ https://earth-and-space-news.blogspot.com/2015/08/august-29-supermoon-kicks-off-three.html

McClure, Bruce. “In 2016, Hunter’s Moon Also a Supermoon.” EarthSky > Tonight. Oct. 15, 2016.
Available @ http://earthsky.org/tonight/first-of-three-supermoons

McClure, Bruce. “Keep Watching Hunter’s Moon on October 16.” EarthSky > Tonight. Oct. 16, 2016.
Available @ http://earthsky.org/tonight/hunters-moon-still-shines-on

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Available @ http://earthsky.org/tonight/is-the-september-2016-full-moon-a-supermoon

McClure, Bruce; Deborah Byrd. “Supermoons of 2016.” EarthSky > Human World > Space. Jan. 5, 2016.
Available @ http://earthsky.org/space/what-is-a-supermoon

McClure, Bruce; Deborah Byrd. “Waxing Toward Full Hunter’s Moon.” EarthSky > Tonight. Oct. 14, 2016.
Available @ http://earthsky.org/tonight/almost-full-hunters-moon-couples-up-with-uranus

Mosher, Jim. “Albedo Feature.” The Moon - Wiki.
Available @ https://the-moon.wikispaces.com/Albedo+feature

Nolle, Richard. “21st Century SuperMoon Alignments.” Astropro > Features > Tables > 21st Century Lunar Tables > SuperMoons. 2000.
Available @ http://www.astropro.com/features/tables/cen21ce/suprmoon.html

Nolle, Richard. “The SuperMoon and Other Lunar Extremes.” The Mountain Astrologer (Oct/Nov 2007): 20-24.
Available @ http://www.mountainastrologer.com/oldfiles/Nolle1007.html

Nolle, Richard. “Supermoon: What It Is, What It Means.” Astropro > Features > Articles. Last updated March 22, 2011.
Available @ http://www.astropro.com/features/articles/supermoon/

Walker, John. “Lunar Perigee and Apogee Calculator.” Fourmilab Switzerland > Earth and Moon Viewer.
Available @ https://www.fourmilab.ch/earthview/pacalc.html

“What Is a Supermoon and When Is the Next One?” Time And Date > Sun & Moon > Moon > Supermoon.
Available @ http://www.timeanddate.com/astronomy/moon/super-full-moon.html