The latest data analysis from the Kepler mission was released earlier today during a NASA teleconference. Among its findings were 11 candidate exoplanets less than twice the diameter of Earth orbiting in their habitable zones and another exoplanet that is one of the closest Earth analogs found to date named Kepler-452b. What makes this so exciting is the fact that it orbits a star (Kepler-452) with similar characteristics to our Sun.
Kepler-452b orbits at a distance of just over 1 AU with a period of 384 days very similar to Earth. Based on modeling, the planet is about five times the mass of Earth plus or minus two Earth masses. It is currently not possible to follow up with radial velocity measurements to get a better fix on its mass. Compared to our Sun, Kepler-452 has a similar mass and temperature with a 10% bigger radius.
The star and planet are estimated to be around 6 billion years old making them 1.5 billion years older than our solar system. At this stage in its evolution, Kepler-452 is becoming brighter and hotter which in turn will increase the surface temperature on Kepler-452b over time. This system could serve as a model for what might happen to Earth as our own Sun ages in a similar manner.
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Recent research has cast doubt on the potential habitability of Kepler 452b. Analysis of its mass and radius suggests that it is unlikely to be a rocky planet as initially suggested. See here for more details.