Moonlight

Moonrise over the Dark Sector Laboratory 5 APR 2012

How you ever wondered what is so special about moonlight?  Few sources of light have so captured the imagination.  Folklore tells us exposure to the light of the full moon will turn a susceptible person into a werewolf or that it makes the symptoms of lunatics (derived from the Latin word luna or moon) much worse.  Hospital staff, Emergency Medicine personnel included, are somewhat superstitious by nature and many will insist a full moon results in an increase in patients with strange symptoms, bizarre behavior, or more babies being born.   

Songs have been written about the moon at least since the 18thcentury.  Beethoven’s Moonlight sonata is perhaps one of the earliest examples.  “By the light of the silvery moon” (1909) or Dean Martin’s classic “When the moon hits your eye like a big pizza pie…” exemplify the modern association of moonlight with the emotion of love.  Objects bathed in moonlight might even be said to take on a somewhat magical quality. 

Balloon Inflation Facility by moonlight

Astronomical twilight ended at the South Pole about a week ago and the only natural illumination is from either from heavenly bodies or auroras.  Moonlight adversely affects aurora study, but it certainly makes it much easier to walk about outside without falling down or tripping over drifted snow.  A full moon is 500,000 times fainter than the sun, but it is amazing how much illumination the moon provides, especially when one considers only about 16% of the sunlight hitting the moon is reflected.   

South Pole Communications Satellite Building by moonlight

Moonlight also has a bluish hue to the human eye as a result of something called the Purkinje effect.  This is because color-sensitive cones in the retina respond best to yellow light, whereas the light-sensitive rods (which are more useful in low illumination settings such as moonlight) respond best to the green-blue portion of the electromagnetic spectrum.  Thus the moon, as well as things illuminated by moonlight, appears bluish.

Amundsen-Scott South Pole Station by moonlight

 With the exception of the photograph taken in early April, you can get a hint of just how dark it is at the South Pole even with moonlight.  I am already looking forward to the Sun’s return in September!

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