Here’s a neat article from Scientific American: When a new extrasolar planet is discovered, how do the artists illustrate a planet they’ve never seen?
When astronomers make a sexy new discovery that doesn’t lend itself easily to visual inspection, they turn to artists like [Lynette] Cook to bring it to life. A compelling image has the power to transform even the most complex data into an easy-to-grasp mental snapshot, but it runs the risk of fooling people into believing an iffy scientific case is closed.
There’s a nice image gallery, and exo-artist Lynette Cook has her own Website which features more of her work.