Transit of Mercury across the sun
Because of its close proximity to the sun, Mercury is often lost in the glare and is usually best seen from Earth only when there's a solar eclipse. From the Northern Hemisphere, you can sometimes see it at dawn or twilight. Transits of Mercury only occur a handful of times within in a century.
Mercury's last transit was in 2016, and the next won't happen again until 2032.
The one you see above was taken this morning, Nov. 11, 2019. The transit occurs from 7:35 a.m. to 1:04 p.m. EST — but please, don't look at the sun directly. A telescope with a solar filter is necessary to spot Mercury during a transit. (You can use solar eclipse glasses for protection, but you will need magnification.)
If you don't have time to stop and see the transit live, you can watch this NASA animation to get a sense of what it's like: