NASA's Finder

Now that individual planets are being detected around distant stars, astronomers are planning on dissecting the light from them to hunt for chemistry that could support or indicate life. Spectral hints of ozone or chlorophyll might be picked up, but these will need precise observations, like those possible with the next generation of space missions such as NASA's Terrestrial Planet Finder. These missions might find us a sister Earth on day, but if they did, would it be populated with humans, fish or dinosaurs, or just contain empty, lifeless continents and seas?"