Stop calling it "the sun" when the sun is as it always has been.
What they're seeing is the passage of "Nemesis" which is not very often and it usually do follow the extinction of life so you know, say your goodbyes.
If you look out into the universe, most systems are binary stars but ours is alone (not) it never was, just that the binary star (Nemesis) is in an elongated orbit so it comes in, stir some shit and leaves for a few billion years and it's back as always. GGWP