A star called KIC 8462852 has recently entered the spotlight after some scientists noticed strange blobs around the star that blocked out some of its light. Undetected planets and even a giant swarm of comets have been considered, but none of them fit the criteria that would cause the phenomenon. Conspiracy theorists considered that it may be even caused by a Dyson sphere, an enormous cluster of solar panels that orbit the star to harvest energy.
Another Non-Alien Explanation
A 2013 research paper by Jason W. Barnes, et al. explains how some stars have non-uniform brightness levels because they're irregularly shaped and "oblate" discs. As the paper continues, “when a star is oblate, it has a larger radius at its equator than it does at its poles. As a result, the poles have a higher surface gravity, and thus higher temperature and brightness. Thus, the poles are ‘gravity brightened’, and the equator ‘gravity darkened. The star becomes oblate (and hence gravity darkening occurs) because the centrifugal force resulting from rotation creates additional outward pressure on the star. This creates patches of darker and lighter regions within these kinds of stars, so the amount of light from the star that makes it back to Earth won't look completely uniform. What's more, planets often orbit 'obliquely' from Earth's perspective and do not pass directly in front of a star." Thus, the non-uniform light from KIC 8462852 could easily be caused by planets passing in front of darker and lighter regions, not by an "alien megastructure."