SCIENTISTS have discovered a planet which could have the most Earth-like environment ever found - raising a 'very compelling case for life there. Gliese 581g, located around 123trillion miles away, orbits a star at a distance that places it squarely in the habitable - or Goldilocks - zone, Nasa said. The research, the product of more than a decade of observations at the WM Keck Observatory in Hawaii, suggests the planet could contain liquid water on its surface. It means it tops the league of planets and moons rated as being most like Earth. With our planet rated at 1.0 on the Earth Compatibility Index, Gliese 581g, found in the Libra constellation, scored 0.89, ahead of Mars on 0.7. But US experts believe Saturns moon, Titan, is still the most likely so far to support life based on surface conditions and whether vital chemical reactions are possible. DM