Sun - September 17, 2006

The Libration of the Earth’s Moon



Wikipedia describes libration and includes a fascinating (simulated) animation of the moon as seen from the Earth over a one-month period. The surprising thing to me is how much the visibility of the moon’s surface varies over a month. Due to actual movements of the moon and changes in the angle of observation, 59% of the moon’s surface can be seen from Earth, not merely a strict “side”.

I find the observed movement of the moon in the animation almost disturbingly wobbly for such a large body (though it doesn’t actually move quite that much.)

Posted at 01:21 PM    

Sat - August 5, 2006

The origin of “chortle”



The word “chortle” was coined by Lewis Carroll in Jabberwocky.

Posted at 12:37 PM    

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