The clues come from the chemical composition of our sun, which differs from that of nearby stars of about the same age. (sciencemag.org)
They hope these bigger projects might be able to directly image Earth - like planets around nearby stars in search of signs of life. (scientificamerican.com)
Most of those detected are located in nearby star forming regions, which are all fairly small and have a low density of stars. (sciencedaily.com)