the quality, production, expression, or realm, according to aesthetic principles, of what is beautiful, appealing, or of more than ordinary significance.
The question of "what is art?" was raised when I found the NASA site, Earth As Art.
Take a look at these earth photos--are they art?
One of the books in our art collection is Looking at Pictures by Susan Woodford [750 WOO]. Of course, by pictures, Woodford is referring to deliberately created art. Still, it might be an educational exercise to read the book and decide whether or not the earth pictures fall into Woodford's concept of art.
Earth images courtesy USGS National Center for EROS and NASA Landsat Project Science Office