Back in 2011, Kepler discovered several planets orbiting within the habitable zone of a sun-like star.
APOD had a great image and explanation about Kepler-22b: “It’s the closest match to Earth that has yet been found. Recently discovered planet Kepler 22b has therefore instantly become the best place to find life outside our Solar System. The planet’s host star, Kepler 22, is actually slightly smaller and cooler than the Sun, and lies 600 light-years from Earth toward the constellation of the Swan (Cygnus). The planet, Kepler 22b, is over twice the radius of the Earth and orbits slightly closer in, but lies in the habitable zone where liquid water could exist on the surface. Pictured above is an artist’s depiction of how Kepler 22b might appear to an approaching spaceship, in comparison to the inner planets of our Solar System. Whether Kepler 22b actually contains water or life is currently unknown. A SETI project, however, will begin monitoring Kepler 22b for signs of intelligence.” (APOD)
Shortly after that, further Earth-sized planets were discovered by Kepler, including two that were orbiting the same star: Kepler-20e and Kepler-20f (NASA). Phil Plait once again reported on it, as did the BBC, New Scientist, and Nature. More recently, in 2013, further planets were discovered, Kepler-62e and 62f (BBC).
In total, since the launch of the mission in 2009, Kepler has discovered more than 1000 confirmed exoplanets in about 440 stellar systems. The New York Times has a great tally of planets discovered by Kepler, showing the relative size of planets, stars, and Mercury’s orbit, as well as the star temperature. It is constantly updated, as is really interesting to look at.
I will leave it here for today, but if you’re interested in learning more about exoplanets, I highly recommend the Exoplanet app for iPhone and iPad. For a free app, there is so much information available to you, it’s fascinating. Onwards!