Ian Sample, science correspondent
Wednesday April 25 2007
The Earth-like Gliese 581C circles a star in the constellation of Libra that is cooler than our sun. Photograph: European Southern Observatory/AP Scientists have discovered a warm and rocky "second Earth" circling a star, a find they believe dramatically boosts the prospects that we are not alone. The planet is the most Earth-like ever spotted and is thought to have perfect conditions for water, an essential ingredient for life. Researchers detected the planet orbiting one of Earth's nearest stars, a cool red dwarf called Gliese 581, 20 light years away in the constellation of Libra.