First Quarter Moon Arises Wednesday, Feb. 25: Second Appearance in 2015

Summary: The first quarter moon makes its second appearance in 2015 on Wednesday, Feb. 25.

first quarter moon portrait by NASA's Lunar Reconnaissance Orbiter (LRO): NASA Goddard Space Flight Center (NASA Goddard Photo and Video), CC BY 2.0, via Flickr

Wednesday, Feb. 25, welcomes the second appearance of the first quarter moon in 2015. The first appearance for 2015 took place from Tuesday, Jan. 27, to Wednesday, Jan. 28.

In actuality, the first quarter moon counts as the moon's third phase in each lunar cycle. The new moon, which ushers in each lunar cycle, is followed by the first quarter's predecessor, the waxing crescent, in which less than half of the moon appears to be illuminated.

For Earthlings, phases of the moon represent the shape of the sunlit portion of the moon as viewed from observers on Earth. The moon travels through eight phases for a complete cycle, which averages 29.5 days. The first quarter moon is followed by five more phases: waxing gibbous, full moon, waning gibbous, last quarter and waning gibbous.

The first quarter moon is classed as the second of the four primary phases in the eight-phase lunar cycle. The new moon has precedence as the first primary phase. The two remaining primary phases, occurring subsequent to the first quarter, are fulfilled by the full moon and the third quarter moon.

The other four phases of the lunar cycle are considered to be intermediate as the moon transitions between primary phases. The waxing crescent moon serves as the transition from new moon to first quarter moon. The waxing gibbous moon serves as the transition from first quarter moon to full moon. The waning gibbous moon serves as the transition from full moon to last quarter moon. The waning crescent moon ends the lunar cycle, serving as the transition from last quarter moon to new moon.

The positions of the moon and of the sun in relation to the Earth determine the progression of lunar phases. The new moon opens the lunar cycle with the sun and moon in conjunction, with the moon's orbit at its closest distance from the sun, as perceived from Earth. The first quarter moon marks the quarter mark in its lunar orbit, at a 90-degree angle with the sun as compared to the Earth.

In its predictable journey through space, away from the sun, around the Earth, and back toward the sun, the moon traces an ellipse, a flattened oval that is astronomy's equivalent to earthly racetracks.

The first quarter moon is known popularly, although inaccurately, as the half moon. As viewed from Earth, the first quarter moon is characterized by 50 percent visibility of the day side of the lunar sphere, which amounts to a true quarter of the moon. For Earth's observers in the Northern Hemisphere, illumination occurs to the right of the terminator, the boundary between light and dark on the moon's near side. For Earth's observers in the Southern Hemisphere, illumination occurs to the left of the terminator.

First quarter moons arise before noon and set after midnight. On Wednesday, Feb. 25, 2015, the first quarter arises around 11 a.m. Its setting occurs around 2 a.m. on Thursday, Feb. 26.

After its setting in February, the first quarter phase of the moon's orderly cycle is scheduled for its third appearance in 2015 on Friday, March 27. The daily greetings of "Good morning, Moon" and of "Good night, Moon" become more meaningfully reassuring through familiarity with the phases of the moon, the Earth's nearest cosmic neighbor.

An illuminating New Year's resolution, possibly far easier to accomplish than some of the daunting projects often envisioned for a new year, would be to give at least a passing glance to the moon every day.

After all, the moon's glow, as gently reflected light, may be viewed directly without harming the viewer's vision.

popular depiction of a "half moon," the first quarter of the moon: 19th Century Trade Cards Collection/Boston Public Library, CC BY 2.0, via Flickr

Acknowledgment

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

Image credits:

first quarter moon portrait by NASA's Lunar Reconnaissance Orbiter (LRO): NASA Goddard Space Flight Center (NASA Goddard Photo and Video), CC BY 2.0, via Flickr @ https://www.flickr.com/photos/gsfc/15982765351/

first quarter ~ ca. 1870-1900 chromolithograph: 19th Century Trade Cards Collection/Boston Public Library, CC BY 2.0, via Flickr @ https://www.flickr.com/photos/boston_public_library/9786544541/