Monday, January 30, 2006

A poser

Here's a little puzzle for those of you who enjoy such things. Above are two "photos" of the Moon, taken at exactly the same instant from London and Paris. The Moon is one-half a degree wide in the sky; i.e. about half as wide as your little finger held at arm's length. How far away is the Moon?

Consider how interesting it is that an answer is possible. The distance to the Moon was first measured by the Alexandrian astronomers of the 3rd century B. C.. It was they who invented in all of its glory what we today call science, a way of thinking that combines abstract thinking, empirical observation, and mathematics that can take us step by step away from the omphalos of our birth into the space and time of the galaxies.

By the way, these are not actual photos; I made them with Starry Night Pro software to illustrate my forthcoming book, Walking Zero: Discovering Cosmic Space and Time Along the Prime Meridian.