New Scientist: First spotted by NASA's Kepler space telescope, KIC 8462852 drew scientific attention because of its erratic changes in brightness. The star dimmed at irregular intervals by up to 20%, whereas most of the stars Kepler saw dimmed regularly and by no more than 1%. One astronomer suggested the variations were caused by aliens constructing a Dyson sphere, a proposal that garnered widespread popular attention. Since then another researcher has dug up archival images revealing a gradual decrease in the star's brightness over the past 100 years. Now, Benjamin Montet of Caltech and his colleagues have examined more Kepler data and found a different dimming behavior. For the first 1000 days of the Kepler mission, KIC 8462852 dimmed at roughly 0.34% per year, twice the rate indicated by the archival images. Then, in just 200 days, the brightness dropped another 2.5% before beginning to level out. The new result makes it even more difficult to find a known phenomenon or combination of phenomena to explain the behavior. The leading explanations include a comet swarm or gas cloud around the star.
