June 2016 Lunar Perigee Is Friday, June 3; Apogee Is Wednesday, June 15

Summary: Moon’s June 2016 lunar perigee, or orbital closeness, happens Friday, June 3, at 10:55 Coordinated Universal Time (6:55 a.m. Eastern Daylight Time).

Moon's elliptical orbit accounts for monthly nearest point (perigee) and farthest point (apogee): NASA Science, Public Domain, via NASA Science/Science News

The moon’s June 2016 lunar perigee (Ancient Greek: περί, perí, “near” + γῆ, gê, “Earth”), when the lunar orbit reaches the month’s closest center-to-center distance between Earth and moon, happens Friday, June 3, at 10:55 Coordinated Universal Time (6:56 a.m. Eastern Daylight Time).

The June 2016 lunar perigee represents a center-to-center distance of 361,142 kilometers (224,403.23 miles). The June 2016 lunar perigee bests the previous month’s perigee by 3,314 kilometers (2059.22 miles). On Friday, May 6, at 4:14 UTC (12:14 a.m. EDT), the previous month’s lunar perigee measured a center-to-center distance of 357828 kilometers (222,344.01 miles).

The June 2016 lunar perigee does not best July 2016’s perigee. The July 2016 lunar perigee bests the June 2016 lunar perigee of 361,142 kilometers (224,403.23 miles) by 8,517 kilometers (5,292.22 miles). On Wednesday, July 27, at 11:25 UTC (7:25 a.m. EDT), the lunar orbit marks a center-to-center distance of 369,659 kilometers (229,695.45 miles).

Next month’s perigee does more than best this month’s perigee. The July 2016 lunar perigee claims the year’s closest center-to-center distance, known as proxigee.

Eccentricities in the moon’s orbit around Earth explain monthly occurrences of perigee and its opposite, apogee (Ancient Greek: ἀπόγειον, apógeion, “away from Earth” + ἀπό, apó, “away” + γῆ, gê, “Earth”). On NASA’s Eclipse Web Site, NASA astrophysicist Fred Espenak, known popularly as “Mr. Eclipse,” gives 363,396 kilometers (miles) at perigee and 405,504 kilometers (miles) at apogee as mean values for variations in the moon’s center-to-center distances from Earth.

Fred Espenak details the moon’s elliptical orbit as having a mean eccentricity of 0.0549. Contrastingly, Earth has an orbital eccentricity of 0.0167. A perfectly circular orbit has an eccentricity of zero. Numbers higher than zero denote somewhat elliptical orbits.

Factors perturbing, or affecting, lunar orbital parameters include gravitational forces between sun and moon and between moon and Earth; changes in distance and relative position between the trio of Earth, moon and sun; lunar orbital inclination; other planets’ gravitational attractions. The lunar orbit inclines, or slants, 5.1 degrees with respect to the plane of Earth’s orbit.

Lunar apogee, or farthest distance, happens Wednesday, June 15, at 12:00 UTC (8 a.m. EDT). The June 2016 lunar apogee measures a center-to-center distance of 405,022 kilometers (251,669 miles).

The June 2016 lunar apogee is closer than the previous month’s apogee. On Wednesday, May 18, at 22:06 UTC (6:06 p.m. EDT), apogee logs a center-to-center remoteness of 405,934 kilometers (252,235.69 miles).

This month’s apogee, though, is farther than next month’s apogee. On Wednesday, July 13, at 5:24 UTC (1:24 a.m. EDT), lunar apogee measures a center-to-center distance of 404,272 kilometers (251,202.97 miles).

The October 2016 lunar apogee claims the year’s farthest apogee. On Monday, Oct. 31, at 19:29 UTC (3:29 p.m. EDT), lunar apogee measures a center-to-center remoteness of 406,660 kilometers (252,686.8 miles). The October 2016 distance bests the June 2016 lunar apogee of 405,022 kilometers (251,669 miles). October’s lunar apogee is 1,638 kilometers (1,017.8 miles) farther than June’s apogee.

The takeaway for the Friday, June 3, lunar perigee and Wednesday, June 15, lunar apogee is the reality of Juliet’s description of the “inconstant moon, that monthly changes in her circled orb” (Act II, scene 2) in William Shakespeare’s popular tragedy, Romeo and Juliet.

comparison of moon at apogee and at perigee; Dr. Tony Phillips, production engineer at NASA Science, explains that perigee moons are 14 percent bigger and 30 percent brighter than apogee moons: NASA Science, Public Domain, via NASA Science/Science News

Acknowledgment

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

Image credits:

moon's elliptical orbit accounts for monthly nearest point (perigee) and farthest point (apogee): NASA Science, Public Domain, via NASA Science/Science News @ http://science1.nasa.gov/media/medialibrary/2008/12/09/09dec_fullmoon_resources/diagram.gif

comparison of moon at apogee and at perigee; NASA production engineer Dr. Tony Phillips explains that perigee moons are 14 percent bigger and 30 percent brighter than apogee moons: NASA Science, Public Domain, via NASA Science/Science News @ https://science.nasa.gov/science-news/science-at-nasa/2011/16mar_supermoon/

For further information:

Espenak, Fred. “2016 Calendar of Astronomical Events.” Astro Pixels > Planetary Ephemeris Data > Calendar of Astronomical Events.
Available @ http://astropixels.com/ephemeris/astrocal/astrocal2016gmt.html

Espenak, Fred. “SkyCal Sky Events Calculator.” NASA Eclipse Web Site > SkyCal.
Available @ http://eclipse.gsfc.nasa.gov/SKYCAL/SKYCAL.html?cal=2016#skycal

“Lunar Perigee and Apogee.” Time And Date > Sun & Moon.
Available @ http://www.timeanddate.com/astronomy/moon/lunar-perigee-apogee.html

Phillips, Tony (Dr.). "Super Full Moon." NASA Science > Science News. March 16, 2011.
Available @ https://science.nasa.gov/science-news/science-at-nasa/2011/16mar_supermoon/

Walker, John. “Lunar Perigee and Apogee Calculator.” Fourmilab Switzerland > Earth and Moon Viewer. May 5, 1997.
Available @ http://www.fourmilab.ch/earthview/pacalc.html

Webb, Brian. “Coordinated Universal Time (UTC).” Space Archive. March 27, 2016.
Available @ http://www.spacearchive.info/utc.htm