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June 26, 2009 -- Scientists looking for Earth-like planets in distant solar systems might find it more productive to focus on pale red dots, rather than blue ones.

So concludes a team of astronomers from Spain and Florida who observed the Aug. 16, 2008, lunar eclipse from a simulated alien perspective and discovered that several biologically relevant molecules, such as oxygen, water, carbon dioxide and methane, show up stronger than expected in longer, redder wavelengths of light.

"The Earth is often referred to as the pale blue dot, but in transmission, the pale blue dot becomes the pale red dot," Enric Palle, with Spain's Instituto de Astrofisica de Canarias, and colleagues wrote in a paper published June 11 in the journal Â Nature.

The team used optical and near-infrared spectrographs attached to telescopes at the El Roque de los Muchachos observatory in the Canary Islands to observe the light reflected from the moon during the eclipse.