Boyajian’s star has been caught in the act of dimming again. But lots of stars appear to drop in brightness from our vantage point on Earth. The graphic below, from Kimberly Cartier and Jason Wright’s article in the May 2017 issue of Scientific American, shows why this case is different.

Credit: Tiffany Farrant-Gonzalez; Source: “KIC 8462852 Faded Throughout the Kepler Mission,” by Benjamin T. Montet and Joshua D. Simon, in Astrophyiscal Journal Letters, Vol. 830, No. 2, Article No. L39; October 20, 2016