There's a little black spot on the Sun today
We were going to exhort you to "Go outside and look at the sun right now!" but some of you would take us up on it and then not be able to read the rest of this mail because we'd permanently damaged your eyes. So instead we'll say, "If you have a telescope with a solar filter and you're not in Australia or the Philippines or that slice of the globe, make sure you catch Mercury's solar transit," which lasts through around 2:30pm ET today. Alternately, everybody can safely watch from NASA's Solar Dynamics Observatory (SDO) transit here.