They have found evidence of larger planets around stars, because of a 'wobble' in the star as it is pulled by the planet's gravity. Simulations of the Alpha Centauri system pointed to planets existing, and they may be more earth-like if they are in a zone around the stars where liquid water can exist. The idea is to compare around 90,000 observations over the next five years, enough so that the 'wobble of a smaller planet can be detected.