Tag Archives: new moon

The Phases of the Moon in Song

Phases of the moon

Carol-Irene Southworth, a student in Professor B’s Solar System class at the University of California at San Diego, wrote and recorded the following song describing the phases of the Moon.  If you want to play along, the chords are just C and F, in this case played on the ukulele (according to Woody Guthrie, “if you play more than two chords, you’re showing off”).

Listen here [4:18m]:

Download here [5.2 Mb]: http://pono.ucsd.edu/~adam/astrofacts/southworth_moonphasesong.mp3

Lyrics are below!

What’s the facts:

Over the course of roughly a month, the part of the Moon that is illuminated goes through a regular cycle of phases.  Starting from dark new moon phase, the Moon gradually brightens, or waxes, through waxing crescent, first quarter, waxing gibbous and finally to a bright full moon phase 14 days later.  The Moon then dims, or wanes, over the next 14 days, going through waning gibbous, third quarter, waning crescent and finally dark new moon again.  This cycle is due to the relative orientation of the Sun, Moon and Earth, and the dark portions of the Moon are always caused by its own shadow shielding the Sun’s rays.  New moon phase happens when the Sun, the Moon and the Earth are in a line, so that the far side of the Moon we can’t see is lit up.  Full moon phase happens when the Sun, the Earth and the Moon are in a line, so we see the sunlit side of the Moon.  The other phases occur in between these two alignments, which are also called syzygy.

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Making Friends with the Night Sky: The New Moon

A glimpse of the moon through the trees, as it phases from new moon to cresent.

A glimpse of the moon through the trees, as it phases from new moon to cresent.

Maui astronomer Harriet Witt describes the new moon, the start of the lunar cycle.

Listen here [3:26m]:

Download here [8.1 Mb]: ftp://space.mit.edu/pub/ajb/radiopio/astrofacts_090722_mfns-moonnew.mp3

What’s the facts:

“A month is a Moonth, a Moonth is a moon.”  For many traditional calendars – Hawaiian, Chinese, Hebrew, Islamic – this is still true, although our western calendar has been tweaked to fit the months into one year.  The new moon is the start of the lunar month, and the time when the moon lies between the Sun and the Earth (this is called syzygy, a great Scrabble word).  Imagine yourself floating out in space well above the Sun, Moon and Earth, and you will see these three bodies in a row, with the Sun-lit side of the Moon facing away from the Earth.  So where is the new Moon in the sky?  Directly in front the Sun!

Why doesn’t the Moon block, or eclipse, the Sun every time the new moon phase happens?  It’s because the plane of the Moon’s orbit is actually inclined by about 5° relative to the plane of the Earth’s orbit (the ecliptic plane).  So most of the time, the Sun, Moon and Earth are out of alignment during new moon.  However, the Moon’s orbit actually rotates, or precesses, every 27.2 days.  So perfect alignment at new moon occurs about once every 18 years, a period the Babylonians called a Saros cycle (a complete explanation can be found here).  In fact, there are several Saros eclipse cycles because the Sun-Moon-Earth alignment doesn’t have to be perfect, so we get about two eclipses at new moon every year.

New moon is a great time for star-gazing as the Sun and the Moon will have both set in the evening.  So be sure to enjoy the dark skies that accompany the new Moon!

Original air date 22 July 2009.