February 2018 Lunar Perigee Is Tuesday, Feb. 27, at 363,938 Kilometers

Summary: February 2018 lunar perigee is Tuesday, Feb. 27, at 363,938 kilometers, the month’s closest center-to-center distance between moon and Earth.

waxing gibbous moon, with nearly 92 percent illumination, at 14:00 UTC, 48 minutes before perigee: Ernie Wright (USRA lead visualizer), John Keller (NASA GSFC scientist), Noah Petro (NASA GSFC scientist) and David Ladd (USRA producer) via NASA/Goddard Space Flight Center Scientific Visualization Studio

February 2018 lunar perigee, which marks the month’s closest center-to-center distance between moon and Earth, is Tuesday, Feb. 27, at 14:48 Greenwich Mean Time/Coordinated Universal Time (9:48 a.m. Eastern Standard Time), at 363,938 kilometers (almost 226,141 miles).

The moon phase at time of perigee is waxing gibbous, the fourth of the eight-phase lunar cycle. As viewed from Earth, the lunar surface displays approximately 92 percent illumination.

Astronomers note the moon’s closest and farthest distances from Earth each month. Perigee (Ancient Greek: περί, perí, “near” + γῆ, gê, “Earth”) represents the closest center-to-center distance between moon and Earth. Its opposite, apogee (Ancient Greek: ἀπόγειον, apógeion, “away from Earth;" from ἀπό, apó, “away” + γῆ, gê, “Earth”), indicates the farthest center-to-center distance between moon and Earth.

Retired NASA astrophysicist Fred Espenak’s Astro Pixels website identifies February’s apogee as an event preceding the month’s perigee by 16 days 32 minutes. February’s moon logged apogee Sunday, Feb. 11, at 14:16 GMT/UTC (9:16 a.m. EST), at 405,701 kilometers. The month’s apogee of 405,701 kilometers is 41,763 kilometers farther than the month’s perigee of 363,938 kilometers.

The moon phase at time of perigee was waning crescent, the eighth of the eight-phase lunar cycle. As viewed from Earth, the lunar surface displayed approximately 16 to 17 percent illumination.

February’s perigee of 363,938 kilometers has a center-to-center distance that is 5,166 kilometers closer than March’s perigee of 369,104 kilometers. March’s perigee happens Monday, March 26, at 17:17 GMT/UTC (1:17 p.m. Eastern Daylight Time).

February’s apogee of 405,701 kilometers has a center-to-center distance that is 1,019 kilometers farther than March’s apogee of 404,682 kilometers. March’s apogee takes place Sunday, March 11, at 09:13 GMT/UTC (5:13 a.m. EDT).

Astronomers also note the year’s minimum and maximum values for perigee and apogee. The year’s closest perigee is also known as proxigee.

The maximum perigee value marks the greatest distance in the closeness range. The maximum perigee for 2018 happens Oct. 31, at 20:05 GMT/UTC (4:05 p.m. EDT), at 370,201 kilometers. The year’s maximum perigee of 370,201 kilometers is 6,263 kilometers farther than February’s lunar perigee of 363,938 kilometers.

The minimum perigee value signifies the smallest center-to-center distance in the closeness range. The minimum perigee value, known as proxigee, for 2018 was achieved Monday, Jan. 1, at 21:54 GMT/UTC (4:54 p.m. EST), at 356,566 kilometers. The year’s proxigee of 356,566 kilometers is 7,372 kilometers closer than February’s lunar perigee of 363,938 kilometers. The year’s farthest, or maximum, perigee of 370,201 kilometers is 13,635 kilometers farther than the year’s proxigee, or minimum perigee, of 356,566 kilometers.

The maximum, or farthest, apogee for 2018 was obtained Monday, Jan. 15, at 02:10 GMT/UTC (Sunday, Jan. 14, at 9:10 p.m. EST), at 406,461 kilometers. The year’s maximum apogee of 406,461 is 760 kilometers farther than February’s lunar apogee of 405,701 kilometers.

The year’s minimum, or closest, apogee is calculated for Sunday, April 8, at 05:32 GMT/UTC (1:32 a.m. EDT), at 404,145 kilometers. February 2018’s lunar apogee of 405,701 kilometers is 1,556 kilometers farther than 2018’s minimum apogee of 404,145 kilometers.

The year’s maximum, or farthest, apogee of 406,461 kilometers is 2,316 kilometers farther than the year’s minimum, or closest, apogee of 404,145 kilometers.

A comparison of 2018’s maximum values reveals a difference of 36,260 kilometers between the year’s maximum, or farthest, apogee of 406,461 kilometers and the year’s maximum, or farthest, perigee of 370,201 kilometers. The minimum values for 2018 present a difference of 47,579 kilometers between the year’s minimum, or closest, apogee of 404,145 kilometers and the year’s minimum, or closest, perigee of 356,566 kilometers.

Perigee and apogee happen because the moon’s orbit of Earth does not trace a perfect circle. The lunar orbit is elliptical. Fred Espenak explains via the NASA Eclipse Web Site: “The Moon revolves around Earth in an elliptical orbit with a mean eccentricity of 0.0549. Thus, the Moon’s center-to-center distance from Earth varies with mean values of 363,396 km at perigee to 405,504 km at apogee.”

The takeaways for February 2018 lunar perigee, happening Tuesday, Feb. 27, at 363,938 kilometers, are that the moon’s elliptical orbit explains variations in center-to-center distance between moon and Earth and that astronomers note monthly closeness (apogee) and remoteness (perigee) as well as the year’s maximum and minimum values.

waning crescent moon, with over 16 percent illumination at 14:00 UTC, 16 minutes before apogee: Ernie Wright (USRA lead visualizer), John Keller (NASA GSFC scientist), Noah Petro (NASA GSFC scientist) and David Ladd (USRA producer) via NASA/Goddard Space Flight Center Scientific Visualization Studio

Acknowledgment

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

Image credits:

waxing gibbous moon, with nearly 92 percent illumination, at 14:00 UTC, 48 minutes before perigee: Ernie Wright (USRA lead visualizer), John Keller (NASA GSFC scientist), Noah Petro (NASA GSFC scientist) and David Ladd (USRA producer) via NASA/Goddard Space Flight Center Scientific Visualization Studio @ https://svs.gsfc.nasa.gov/vis/a004600/a004604/frames/5760x3240_16x9_30p/fancy/comp.1383.tif

waning crescent moon, with over 16 percent illumination at 14:00 UTC, 16 minutes before apogee: Ernie Wright (USRA lead visualizer), John Keller (NASA GSFC scientist), Noah Petro (NASA GSFC scientist) and David Ladd (USRA producer) via NASA/Goddard Space Flight Center Scientific Visualization Studio @ https://svs.gsfc.nasa.gov/vis/a000000/a004600/a004604/frames/5760x3240_16x9_30p/fancy/comp.0999.tif

For further information:

Barnes, Joshua E. “Shape of Lunar Orbit.” March 11, 2003. University of Hawaii Institute for Astronomy > Barnes > Astronomy 110 Laboratory.
Available @ https://www.ifa.hawaii.edu/~barnes/ASTR110L_S03/lunarorbit.html

Espenak, Fred. “Eclipses and the Moon’s Orbit.” NASA Eclipse Web Site > Solar Eclipses.
Available @ https://eclipse.gsfc.nasa.gov/SEhelp/moonorbit.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. “2018 Calendar of Astronomical Events Greenwich Mean Time.” Astro Pixels > Ephemeris.
Available @ http://astropixels.com/ephemeris/astrocal/astrocal2018gmt.html

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

Marriner, Derdriu. “2017 Lunar Apogee Maximum Happens Dec. 19 at 406,605 Kilometers.” Earth and Space News. Wednesday, Dec. 13, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/12/2017-lunar-apogee-maximum-happens-dec.html

Marriner, Derdriu. “2017 Lunar Apogee Minimum Happens Aug. 30 at 404,307 Kilometers.” Earth and Space News. Wednesday, Aug. 23, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/08/2017-lunar-apogee-minimum-happens-aug.html

Marriner, Derdriu. “2017 Lunar Perigee Maximum Happens Sept. 13 at 369,856 Kilometers.” Earth and Space News. Wednesday, Sept. 13, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/09/2017-lunar-perigee-maximum-happens-sept.html

Marriner, Derdriu. “2017 Lunar Perigee Minimum Happens May 26 at 357,210 Kilometers.” Wednesday, May 24, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/05/2017-lunar-perigee-minimum-happens-may.html

McClure, Bruce. “Close and Far Moons in 2018.” EarthSky > Astronomy Essentials. Jan. 15, 2018.
Available @ http://earthsky.org/astronomy-essentials/close-and-far-moons

“Moon Phases February 2018.” Calendar-12.com > Moon Calendar > 2018.
Available @ https://www.calendar-12.com/moon_calendar/2018/february

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