It always helps to keep these things in perspective.
Besides, like so many other celestial events involving the sun, this one comes with a catch: You can't look directly at it, or you'll go blind!! That means you have to go out and buy #5 welders glasses, or set up those stupid pinhole contraptions, or trick someone you don't like into staring directly at it and providing you with a blow-by-blow description.
Unless, of course, you happen to live in the western United States. The transit will be taking place before sunrise there, so you'll be able to watch it without fear of going blind.
That reminds me.... How do blind people who are allergic to dogs get around?
Saturn.... Which has absolutely nothing to do with Venus but looks way cooler
These so-called Venus transits take place in predictable intervals, and back in the 18th & 19th centuries, scientists tried to take advantage of them to calculate the distance of the Earth to the sun. The theory goes that if you position several observers around the Earth, and have them record the exact times the transit ends, you can calculate the various angles and distances involved. Of course, such primitive methods provided them with wildly inaccurate estimates. It wasn't until the dawn of the space age when astronauts were finally able to compute the now accepted distance of 92,955,887.6 miles by laying a whole shitload of rulers end to end.