The discovery of the icy exoplanet OGLE-2005-BLG-390Lb (just 5 times more massive than Earth) by the technique of gravitational microlensing provided the first observational hint that Earth-like planets are common in the Universe. The existence of this new world was revealed from a small blip in the brightness of the star, on just one night, but we will probably never be able to see it again by this method. read more »