Eight Phase Moon Cycle Is Natural Navigation Aid for Finding Direction

Summary: The eight phase moon cycle serves as a natural navigation aid for finding direction on the moon’s parent body, Earth.

Rising full moon marks east over Rio Arriba Couny, northwestern New Mexico, Tuesday, March 26, 2013, 19:19:28: Mike Lewinsky (ikewinski), CC BY 2.0 Generic, via Flickr

The eight phase moon cycle, which repeats monthly from Earth’s perspective, serves as a natural navigation aid for finding direction on Earth as the lunar parent body.

Natural navigator Tristan Gooley promotes accurate determination of direction by way of nature’s clues. One of the natural navigation aids identified by Gooley is the 360-degree, eight phase moon cycle.

The new moon signals the beginning of the monthly lunar cycle. The moon then successively phases from newness to waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last (or third) quarter and waning crescent. New, first quarter, full and last quarter compose the cycle’s four principal phases. Waning crescent, waxing gibbous, waning gibbous and waning crescent represent four intermediate phases, which transition between two principal phases.

Each phase distinctively illuminates the lunar surface. After the new moon, increasing illumination, with less than half for waxing crescent, 50 percent for first quarter and more than one-half for waxing gibbous, culminates in complete illumination in the full moon. After fullness, illumination decreases, measuring more than half for waning gibbous, 50 percent for last quarter and less than one-half for waning crescent.

The geometric appearance of each phase’s illumination also is distinctive. In the Northern Hemisphere, the right side of the lunar surface is lit during post-new moon phases of waxing crescent, first quarter and waxing gibbous. At northern latitudes, the left side is illuminated during post-full moon phases of waning gibbous, last quarter and waning crescent.

The eight phase cycle begins in mid-November 2017 with onset of the moon’s new phase. Newness happens Saturday, Nov. 18, 2017, at 11:42 Coordinated Universal Time, the world’s official time standard. The event takes place at 6:42 a.m., according to Eastern Standard Time (EST), the time zone for the United States’ national capital of Washington DC.

The new moon is an invisible moon. Located in the same direction in the sky as the sun, the moon faces Earth with its unilluminated side. Its illuminated side faces away from Earth and toward the sun.

Although invisible, the new moon reveals direction by way of the sun. At midday, the instant of the sun’s highest position in the sky, the new moon and the sun reside due south in northern latitudes. In their duet during the moon’s new phase, the invisible moon and the glaringly visible sun perch close to east at sunrise and close to west at sunset.

The first quarter phase happens Sunday, Nov. 26, 2017, at 17:03 UTC (12:03 p.m. EST). The first quarter moon trails the sun by 90 degrees, one-quarter of a complete cycle of 360 degrees. Sunset occurs in the west, which marks 270 degrees in the complete, north-east-south-west cycle of 360 degrees. Behind by a distance of 90 degrees, the first quarter moon signals due south, at 180 degrees.

The full moon phase takes place Sunday, Dec. 3, 2017, at 15:47 UTC (10:47 a.m. EST). The full moon’s position opposite the sun means the duet of moonrise with sunset and moonset with sunrise. As the sun sets in the west, the full moon rises in the east. At midnight, the invisible sun is due north, so the visible, full moon approximately marks due south.

The last quarter phase happens Sunday, Dec. 10, 2017, at 07:51 UTC (2:51 a.m. EST). The last quarter moon is at 270 degrees, three-fourths of the way through the 360-degree cycle. With the sun at 180 degrees, the last quarter phase is described as so far behind that it actually also may be viewed as 90 degrees ahead of the sun. At sunset, with the sun marking west, the last quarter moon, positioned 90 degrees ahead, indicates due north.

The takeaway for the eight phase moon cycle as a natural navigation aid for finding direction is that Earth’s moon provides not only decorative lighting but also practical guidance to moongazers.

360-degree, eight phase lunar cycle: NASA, Public Domain, via NASA Space Place

Acknowledgment

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

Image credits:

Rising full moon marks east over Rio Arriba Couny, northwestern New Mexico, Tuesday, March 26, 2013, 19:19:28: Mike Lewinsky (ikewinski), CC BY 2.0 Generic, via Flickr @ https://www.flickr.com/photos/ikewinski/8594980399

360-degree, eight phase lunar cycle: NASA, Public Domain, via NASA Space Place @ http://spaceplace.nasa.gov/review/dr-marc-earth/moon-phases.html

For further information:

“2017 Phases of the Moon.” U.S. Naval Observatory Astronomical Applications Department > Phases of the Moon.
Available @ http://aa.usno.navy.mil/cgi-bin/aa_phases.pl?year=2017&month=1&day=1&nump=50&format=p

“Event in UTC on Saturday, November 18, 2017 at 11:42:00 a.m.” Time And Date > Time Zones > World Clock > Event Time Announcer.
Available @ https://www.timeanddate.com/worldclock/fixedtime.html?iso=20171118T1142&p1=1440

Gooley, Tristan. The Lost Art of Reading Nature's Signs: Use Outdoor Clues to Find Your Way, Predict the Weather, Locate Water, Track Animals -- and Other Forgotten Skills. New York NY: The Experiment, 2015.

Gooley, Tristan. The Natural Navigator: The Rediscovered Art of Letting Nature Be Your Guide. New York NY: The Experiment, 2012.

Gooley, Tristan. The Natural Navigator: A Watchful Explorer’s Guide to a Nearly Forgotten Skill. New York NY: The Experiment, 2011.

“Phases of the Moon and Percent of the Moon Illuminated.” U.S. Naval Observatory Astronomical Applications Department > FAQ > Phenomena of the Sun and Moon.
Available @ http://aa.usno.navy.mil/faq/docs/moon_phases.php