NASA Press Conference
Entry posted by Letagi
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That was slightly underwhelming, but cool nonetheless.
The new Kepler discovery was exactly what I and most others expected it to be - the most habitable exoplanet found to date, but with no signs of life.
The planet, Kepler-452b, is the only planet found so far in the Kepler-452 system, 1400 light years from Earth. It was discovered using the transit method, where the apparent brightness of a distant star decreases slightly (usually by about one part in 10,000) when an orbiting planet passes between it and Earth. If this happens at regular intervals, then further methods of analysis are used to determine whether it is in fact a planet (since the same effect can be caused by binary star systems and other phenomena).
Kepler-452b has a mass of 5±2 Earth masses, a radius 60% larger than Earth and a corresponding surface gravity of about 2g (with an error margin related to the error margins for mass and size, but I'm too lazy to calculate that). Its orbit is 5% larger in radius than that of Earth and lasts 385 Earth days, but its star is older and thus more active, and so the planet receives 10% more solar radiation than Earth. This would cause an Earth-size planet at the same location to be undergoing a runaway greenhouse effect, similar to Venus, but Kepler-452b's larger mass means that won't happen for another 500 million years or so (if our observations are correct; there's a possibility we're slightly off somewhere, and it is indeed happening now).
Currently, the technology for analysis of atmospheric composition of exoplanets doesn't exist. It's not beyond our current capabilities - we just haven't built a big enough telescope yet. Thus, we have no idea what the atmosphere of Kepler-452b is made of. If future findings show it to have dioxygen and/or methane in significant quantities, it will be an excellent candidate for life as we know it.
-Letagi
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