https://www.scientificamerican.com/article/the-mercury-transit-of-2019-has-begun/

Grab your solar eclipse glasses or protected astronomical equipment, because Mercury is marching across the sun as we speak.

The closest planet to the sun began its transit—an apparent passage across the sun from the perspective of Earth—at 7:35 a.m. EST (1235 GMT) and will continue its journey for 5.5 hours. It will be visible in the U.S.and many other parts of the world. Be sure to check this event out, as it will be the last time until 2032 that Mercury transits the sun. And that occurrence  won’t be visible in the U.S.; Americans will have to wait until 2049 for the next visible event.