ScuttleMonkey from the best-discoveries-by-accident dept.
The rover Spirit has been dragging one wheel around the surface of Mars for some time. One of the resulting gouges revealed a mineral deposit which was probably caused by a hydrothermal vent. This implies a large amount of water was present when the vent was active.
The best book on programming for the layman is "Alice in Wonderland";
but that's because it's the best book on anything for the layman.