Here is a link to learn the latest on habitable zone exoplanets that are similar in size to Earth.
These are planets where liquid water can exist as the planet lies in the zone around its star that allows for liquid water. The study finds that this is a fairly common happenstance in our Milky Way Galaxy with tens of billions of such planets.
Read More About It: http://newscenter.berkeley.edu/2013/11/04/astronomers-answer-key-question-how-common-are-habitable-planets/
Sky Guy Headed To Sea Again On Another Transatlantic Crossing