There is a low level but prescient rumor in some area that aliens are damaging windshields in cars. Go look at the windshield of your car and see if there are hundreds of little pits in them.
The pits change the characteristics of the light heating up the inside of the car on a summer day enough that several automotive engineering groups have had to deal with it. Typically it means doing something different with plastic. One example is the plastic covers over those auto belt things in the mid 80s where the plastic was deteriorating faster in cars with more damage to the windshield was mentioned in a an article in an automotive safety journal. The pits also mean the glass gets hotter as it ages so the frame has to compensate.
A vast majority of the pits are caused by tires throwing small bits of rock at an angle to the glass. The small bits of rock also seem to be tracked in from far away and aren't from the local road surface.
So when the light output goes way down, will someone also blame the aliens?