That Tiny Dot? It’s the 2019 Transit of Mercury

"The planet Mercury slid across the face of the sun on Monday. Mercury is the fastest planet, and if it orbited on the same plane as Earth we would see it pass in front of the sun every 166 days. But Mercury’s orbit is tipped, so we only see it cross the sun in the rare November or May when Mercury rises or falls directly between the Earth and sun. Mercury appeared as a tiny black dot at 7:35 a.m. Eastern time. Its full transit across the sun took five and a half hours. Transits of Mercury happen about 13 times a century. Here are all transits since 1900. November transits are angled upward, as Mercury rises above the plane of Earth’s orbit. During these transits Mercury is close to the sun and moving quickly. ..."
NY Times
NY Times: How to Watch Mercury’s 2019 Transit of the Sun (Video)

An observation of the 1631 Mercury transit by Pierre Gassendi.