I wanted to take a moment to remind everyone about the Venus transit today. In the US, it starts around sunset on the east coast and around 3PM on the west coast. During a Venusian transit, Venus passes directly between the Earth and the Sun, appearing as a small black dot moving slowly across the surface of the Sun. It should take around 7 hours to complete.
As with the solar eclipse last month, it is not safe to stare directly at the Sun. To directly view the transit, you'll either need a pair of #14 welder's glasses, special disposable glasses designed for viewing eclipses. Alternately, you can use a pair of binoculars or a pinhole lens to project an image of the Sun on a piece of white paper. DO NOT STARE DIRECTLY AT THE SUN, or you're gonna have a bad time.
This is the last Venusian until 2117, so if you want to see a Venus transit, make sure you get outside sometime this afternoon. Local times for the transit have been posted here. If you're not somewhere you can see the sky, NASA is running a live stream from the Mauna Kea Observatory in Hawaii.
It may interest you to know that the most famous transit of the Sun by Venus happened in 1761, when Sir Edmund Halley (the same Halley who computed the orbit of Halley's Comet), and a massive team of scientists travelled to different latitudes around the globe to view the transit. They brought the most precise clocks available at the time, and measured the length of time the transit took. When the data was tabulated, this let them calculate the distance from the Earth to the Sun.
So that's why a transit of Venus is more than just a scientific curiosity.