Kepler Space Telescope discovers an Earth-like planet
Kepler-22b has a radius around two and a half times that of Earth, and yet is the smallest extra-solar planet ever found in the habitable zone of a distant star. It also has a similar orbital period - 290 days, as compared to Earth's 365 days. In addition, the parent star it orbits is also very similar to the Sun - it too has a spectral class of G.
The Kepler Space Telescope was launched in March 2009, and is currently observing over 150,000 stars across the night sky. It works by looking for tiny drops in the light coming from a star, as an orbiting planet passes in front of it. This is known as the Transit Method of detection. If the light dips recur on a regular basis, then there's a good chance of a planet orbiting around the host star. In the two years of operation, NASA has indicated that the Kepler telescope has found a total of 2,326 possible planets, of which 207 could be Earth-sized, and more importantly, 10 of which are thought to live in the habitable zone.
The recent discoveries have renewed hope that one day we might find life elsewhere in the Universe.