Moon Phases: Shapes of the Moon

Moon Phases

These are the phases of the moon as seen from the earth. The moon takes about 29 days to orbit the earth and pass through these phases. (The exact length of this cycle is 29 days, 12 hours, 44 minutes, and 3 seconds.)

Spend 29 nights or a lunar month observing the phases of the moon.

crescent moon--a phase of the moon occurring before and after the dark of the moon, when only a thin, curved section is lighted by the sun. The crescent moon visible after the "dark of the moon" is known as the waxing crescent moon or sometimes the young crescent moon. The crescent moon visible before the dark of the moon is known as the waning crescent moon or sometimes the old crescent moon.

dark of the moon--the phase of the moon when it is directly between the sun and the earth. Because sunlight is hitting only the far side of the moon, it appears dark from the earth--basically it is invisible at this phase. Modern astronomers have divided the moon's cycle into four phases (new, first quarter, full, and last quarter) and refer to this phase as the new moon.

first quarter moon--see waxing half moon. Modern astronomers have divided the moon's cycle into four phases (new, first quarter, full, and last quarter).

full moon--the phase of the moon when it is on the opposite side of the earth from the sun and receives sunlight across the moon's entire face, forming a circle of light with the entire lunar disk. Astronomers state that the moon is in opposition to the sun during the full moon phase.

gibbous moon--the phase of the moon occuring before and after the full moon. At this phase, the moon is getting larger after the phase of the waxing half moon (aka the first quarter moon) or smaller after the full moon, but before the waning half moon (aka the last quarter moon).

half moon--the phase of the moon that can be either the waxing half moon or the waning half moon. The phase occurs when the moon is 90 degrees away from the line between the earth and the sun. The angle of illumination creates a half circle, with the lighted half being on the right side during the waxing half moon and on the left side during the waning half moon.

last quarter moon--see waning half moon. Modern astronomers have divided the moon's cycle into four phases (new, first quarter, full, and last quarter).

new moon--see dark of the moon. Modern astronomers have divided the moon's cycle into four phases (new, first quarter, full, and last quarter).

old crescent moon--another name for the thin crescent moon that is still visible before it passes out of sight during the dark of the moon. See waning crescent moon.

quarter moon--see half moon. Modern astronomers have divided the moon's cycle into four phases (new, first quarter, full, and last quarter).

waning moon--the period of the moon's cycle after the full moon and before the moon disappears at the time of the dark of the moon. During this period, the illuminated portion of the moon's surface is decreasing.

waning crescent moon--a period of the lunar cycle which occurs after the waning half moon, when the moon diminishes in light, forming a crescent shape until the lunar disk disappears at the dark of the moon. It is sometimes referred to as the old crescent moon.

waning gibbous moon--a period of the lunar cycle occuring after the full moon as the lunar disk diminishes to the shape of a waning half moon. During this period, the moon appears hump-backed.

waning half moon--the phase of the moon when it is 90 degrees away from a line between the earth and the sun. The angle of illumination creates a half circle, with the lighted half being on the left side of the lunar disk. Modern astronomers have divided the moon cycle into four phases (new, first quarter, full, last quarter) and refer to this phase as the last quarter.

waxing moon--the period in the moon's monthly cycle after the dark of the moon, after the lunar disk becomes visible again until the full moon. During this period, the illuminated portion of the moon's surface is increasing.

waxing crescent moon--a period of the lunar cycle which occurs just after the moon becomes visible in the sky, reappearing after the dark of the moon, during which the lunar disk increases in light until it reaches the shape of the waxing half moon. It is sometimes referred to as the young crescent moon or the new crescent moon. during this time, the crescent shape is illuminated on the right side of the lunar disk, with the horns facing left or sometimes up.

waxing gibbous moon--a period of the lunar cycle after the phase of the waxing half moon, as the lunar disk increases to the full moon. During this period, the moon appears hump-backed.

waxing half moon--the phase of the moon when it is 90 degrees away from a line between the earth and the sun. The angle of illumination creates a half circle, with the lighted half being on the right side of the lunar disk. Modern astronomers have divided the moon cycle into four phases (new, first quarter, full, last quarter) and refer to this phase as the first quarter.

young crescent moon--another name for the thin crescent of the moon that becomes visible, reappearing after the dark of the moon. Sometimes this slender crescent is called the new crescent moon.

Copyright 2004, 2008 Myth Woodling

Sources:
Michael Zeilik, Astronomy: The Evolving Universe, 1976
Kim Long, The Moon Book, 1988

Go to index page