A familiar atmosphere with a few alien quirks.
Everything scientists know about this alien world comes from the way it interacts with its star. The Kepler mission first spotted the star’s dimming in 2015, and follow-up observations with the Spitzer space telescope confirmed presence of a planet twice as large as Earth in 2017. A different instrument then weighed the planet by measuring the star’s wobble, finding it to be about eight times heavier than Earth. Another three years of observations with the Hubble Space Telescope managed to capture eight more flickers of light, leading to this week’s descriptions of the planet’s atmosphere.