We may finally know why Betelgeuse dimmed so much. Bonus: No supernova. Yet.

In late 2019 and early 2020 the star Betelgeuse started behaving badly. Normally one of the very brightest stars in the sky, it dimmed drastically, and for a few weeks dropped in brightness to less than a quarter its normal luster.

Then, just as suddenly, it began to brighten again. While it took a second, far smaller dip in June/July of 2020, it is now back to its usual ruddy glow marking the left armpit of Orion*.

Because it's such a showy star, and easily observable all over the planet — no...