Mercury is passing in front of the sun in a phenomenon known as a “transit”. And you say, big deal, it passes in front of the Sun all the time. That’s what Mercury does, from our perspective. Well, the thing is, right now you can actually see the tiny planet cast its shadow on the Sun, which is not something you can see all the time — only once every few years, on average. NASA has some photos up right now. Please look at these instead of going out and staring, slack-jawed, directly at the sun.
The bad news here is that if it’s past about 8am on the East Coast of the US, you’ve already missed it (and quite obviously if you’re on the West Coast, you won’t see it live at all). Be that as it may, you should at least be aware it happened. And, look, NASA put together a movie of it for you. Now, go on with the rest of your day.