How to safely watch Mercury's 5-hour transit across the sun

The solar system’s smallest planet will appear as a tiny black speck slinking across the sun Monday morning, in a rare celestial event. The transit of Mercury, the innermost planet, began Monday morning around 7:35 a.m. EST. Weather permitting, the planet’s trip across the sun will be visible to most of the world for more than five hours. “Though it takes Mercury only about 88 days to zip around the Sun, its orbit is tilted, so it’s relatively rare for the Sun, Mercury an