Space.com (October 5, 2009)
"The moon, so bright and large in the sky compared to other celestial objects, has captured the attention of humans at least since the dawn of consciousness. Over these eras, mankind's view of the moon has evolved, from the more mystical image of it as a god, to the thought it was covered in seas and vegetation. Most recently, it's been viewed as a dry and dusty wasteland.
"Recent findings of water on the lunar surface could spur yet another shift in the way we see our orbiting companion.
"The moon appears in early art thousands of years ago, showing that early man was as enthralled by its eerie glow as later philosophers and scientists.
"The moon, like the sun and the five planets visible to the naked eye, was wrapped into the mythology of many ancient cultures, and considered a deity by some — to the Egyptians it was Thoth, to the Greeks, Artemis, and to the Hindus, Chandra...."
The idea that there might be water, and other easily-evaporated substances, near the moon's surface made sense: and was taken fairly seriously up until the moon rocks were analyzed. One of the models showed how water, for example, could be chemically bound in the sort of rock the moon seemed to be made of.
Now, going back to the moon with another set of instruments - and about 40 years to think about what to look for - we've found water. The question now is: how much?
I appreciated the way Space.com walks the reader through the last two-dozen (roughly) centuries of serious consideration of what the mooon's like.
"...Since Aristotle, the prevailing school of thought held that the heavens were more perfect than the Earth and therefore all celestial bodies, including the moon, were perfectly smooth spheres...."
There's no question that Aristotle was a smart man. He had a lot on the ball. On the other hand, I wonder if he ever looked, hard, at the moon. With middling-fair vision, it's hard to miss those irregular blotches on the 'perfectly smooth sphere' up in the sky.
It could be a case of love of an attractive idea trumping evidence. Or, maybe Aristotle was near-sighted. Or, something else. Reflections, maybe? A perfectly smooth surface would, presumably, be a pretty good mirror - Never mind what a spherical mirror would do to the image it reflects.
The article has its light side too: including this explanation for 'the moon is made of (green) cheese:
"...No astronomers ever believed the notion that has entered pop culture that the moon is made of green cheese. The phrase comes from an old proverb that makes fun of the overly-credulous, namely those that see the reflection of the moon in the water and think it is a wheel of green (or young) cheese. ..."
There's probably a better, more comprehensive, easier-to-read summary of what we've known about the moon over the millennia - but this is a pretty good one.
- "Water, Water Everywhere - Even on the Moon - Again"
(September 28, 2009)
- "Water, Water Everywhere - Even on the Moon"
(September 24, 2009)
- "Working on the Moon? Pack a Blanket"
(May 26, 2009)
- "R & D & Rovers: Back to the Moon and Mars"
(May 18, 2009)
- "Hordes of Italian Robots on the Moon: It Could Happen"
(May 14, 2009)
- "Spaceship to the Moon: This One's from India"
(October 22, 2008)
- "How Planets Formed - Current Ideas"
(May 18, 2008)