Mercury Transit and 'Demon Star' Dims in November 2019 Skywatching

Learn all about the Mercury Transit on November 11. Also this month, you can "observe the regular dimming and brightening of the 'Demon star,'" according to NASA's Jet Propulsion Laboratory. -- Mercury Transit 2019: Here's Why This Celestial Event Is So Rare: https://www.space.com/mercury-transit-2019-why-its-rare.html

Algol animation is licensed as CC-BY-SA 3.0. Video credit NASA-JPL/Caltech.