Blue Moon

Blue Moon

A relaxed love song written in the mid-1930s by Lorenz Hart for a tune by Richard Rogers. Elvis Presley recorded this song in the 1950s, Frank Sinatra did the same in the 1960s, and many other less famous names have done the same since it was written.

Beautiful.

Blue moon, you saw me standing alone,
Without a dream in my heart,
Without a love of my own.

Blue moon, you knew just what I was there for,
You heard me saying a prayer for,
Someone I really could care for,

    And then there suddenly appeared before me,
    The only one my arms will ever hold.
    I heard somebody whisper, "Please adore me,"
    And when I looked the moon had turned to gold,

Blue moon, now I'm no longer alone,
Without a dream in my heart,
Without a love of my own.

I have always thought the same that IvyNeko and nealesa have written about this node, however, I have a meteorology textbook that offers a different explanation than theirs. I find it interesting and would like to share:

The scattering of light by large quantities of atmospheric particles can cause some rather unusual sights. If the volcanic ash, dust, smoke particles, or pollutants are roughly uniform in size, they can selectively scatter the sun's rays. Even at noon, various colored suns have appeared: orange suns, green suns, and even blue suns. For blue suns to appear, the size of the suspended particles must be similar to the wavelength of visible light. (This situation produces a type of scattering called Mie scattering.) When these particles are present they tend to scatter red light more than blue, which causes a bluing of the sun and a reddening of the sky. Although rare, the same phenomenon can happen to moonlight, making the moon appear blue; thus, the expression "once in a blue moon."

Source: Ahrens, Donald C. Meteorology Today: An Introduction to Weather, Climate, and the Environment. Pacific Grove, CA: Brooks/Cole, 2000. Page 86.

Please also take a look at The Cow's blue moon writeup for more insight.

Astronomical Blue Moon

Technically speaking, there are twelve names given to the full moon - one for each month of the year. Since a lunar month is shorter than a solar month, there are sometimes 13 full moons in one year. The name "Blue Moon" was used in years which had this extra full moon. It specifically refers to the third full moon of four that occurs between an equinox and solstice of that year. In 1943, this technical definition was misinterpreted by Sky and Telescope Magazine, where they defined a Blue Moon as the name given to the second full moon in a calendar month. Since then, this mistaken definition has become the more commonly known definition for the term.

Because a lunar month is approximately 29.5 days, it is somewhat uncommon for a blue moon to occur, and in fact they occur with almost the same frequency under each definition. While the term "once in a blue moon" has come to signify a very rare occurence, on average, they actually occur about every 2.5 to 2.75 years.

Using the more modern definition, it is possible for two blue moons to occur in a single calendar year. This event is much more rare, occurring only about four times per century in a year where February has no full moon. This double blue moon can occur in January/March, January/April, or January/May. It is possible for a blue moon to occur in December of one year and one to occur in March of the next year as well. This December/March combination also requires that February has no full moon.

Blue Moon Calendar

1950-1999           |  2000-2050
--------------------+--------------------
May 31, 1950        |  November 30, 2001
December 31, 1952   |  July 31, 2004
October 31, 1955    |  June 30, 2007
July 30, 1958       |  December 31, 2009
January 31, 1961*   |  August 31, 2012
April 30, 1961*     |  July 31, 2015
November 30, 1963   |  January 31, 2018*
August 31, 1966     |  March 31, 2018*
May 31, 1969        |  October 31, 2020
December 31, 1971   |  August 31, 2023
October 31, 1974    |  May 31, 2026
July 30, 1977       |  December 31, 2028
March 31, 1980      |  September 30, 2031
December 30, 1982   |  July 31, 2034
July 31, 1985       |  January 31, 2037*
May 31, 1988        |  March 31, 2037*
December 31, 1990   |  October 31, 2039
September 30, 1993  |  August 31, 2042
July 30, 1996       |  May 30, 2045
January 31, 1999*   |  January 31, 2048
March 31, 1999*     |  September 30, 2050

*A double Blue Moon (i.e., two Blue Moons in one calendar year)

See also: Black Moon

Literal Blue Moon

While the definition of a blue moon above has nothing to do with the actual appearance of the moon, there are phenomena that can cause the moon to actually appear bluish in color. High concentrations of dust particles in the atmosphere can cause the light of the moon to appear blue. It is said that following the eruption of Krakatoa in 1883, such a blue moon (sometimes green moon) could be seen around the world for nearly two years. In some cases during this time period, even the sun itself appeared blue.

References

• http://www.infoplease.com/spot/bluemoon1.html
• http://www.griffithobs.org/IPSBlueMoon.html
• http://nssdc.gsfc.nasa.gov/planetary/lunar/blue_moon.html
• http://www.farmersalmanac.com/astronomy/moonnames.html
• http://www.opticsforkids.org/resources/Scattering_2.pdf

Background

Song by Alex Chilton on Big Star's Third/Sister Lovers album. Recorded in 1974 at Ardent Studios in Memphis, Tennessee but only released in 1978, this is one of the best moments on the record, with a sparse arrangement featuring only Chilton's voice, a fingerpicked acoustic guitar, an acoustic bass and some woodwinds arranged by Carl Marsh. The chord sequence resembles Pachelbel's Canon very closely, varying only in the use of the relative minor instead of the root as the penultimate chord:

Blue Moon:
I - V - vi - IV - iii - IV - V - vi - IV, in the key of C

Canon:
I - V - vi - IV - iii - IV - V - I - IV - V, in the key of D

In chord terms, the song is played C G Am Em F G Am F.

It follows the similarly-themed Nightime and is followed by the final track on the album, Take Care. In the midst of the raw chaos that is Third/Sister Lovers, Blue Moon is a great break from it all, a step back to reflect on something similar. It's instantly familiar (probably because of the above-mentioned similarity to the Canon) but not tritely so. It's Big Star at its best.

Lyrics

Let me be your one light
And if you'd like a true heart
Take the time to show you're mine
And I'll be a blue moon in the dark

While you sleep, you'll see me there
Clouds race across the sky
Close your eyes and don't ask why
And I'll be a blue moon in your eyes

Morning comes and sleeping's done
Birds sing outside
If demons come while you're under
I'll be a blue moon in the sky

When a month has two full moons, the second one is called a blue moon.

This blue moon cycle is 2.72 years, or roughly every third year. This is not at all unusual, but when it happens on New Year's Eve, as it will on December 31, 2009 in the Western Hemisphere, this is a bit rarer as it is a 19-year occurrence. The last such one occurred in 1990, the next one will not be until 2028.

Australia and Asia, being in the Eastern Hemisphere, will not experience it until January 1. On New Year's Eve, with a new decade being introduced, there will also be a partial lunar eclipse. This not be visible in the Western Hemisphere but will be viewed by people in the Eastern Hemisphere.

Chances are the moon viewed on the night of December 31, 2009/January 1, 2010 will not be blue in the meterology sense, but it will qualify for the "Once in a blue moon" title.

www.huffingtonpost.com/wires/2009/12/29/rare
http://en/wikipedia.org/wiki/Blue_moon