Alpha Centauri may have two Earth-like planets

New Scientist : In 2012 researchers announced that they may have found a planet orbiting Alpha Centauri B. The finding was based on slight wobbles observed in the star’s motion and suggested the planet orbited the star every three days. A subsequent set of observations in 2013 and 2014 by Brice-Oliver Demory of the University of Cambridge and his colleagues, who used the Hubble Space Telescope to look for a dimming of the star’s light, revealed a single transit of Alpha Centauri B. However, the duration of the transit was longer than had been predicted for the planet. Demory’s team ruled out other phenomena to explain the transit, which suggests the existence of a second planet in orbit around Alpha Centauri B. Confirming the second planet won’t be easy because it would require 20 consecutive days of observations with Hubble. Given the many demands for time on the telescope, approval for such a long observation is unlikely.