Don't go blind today trying to watch Mercury transit the Sun because it cannot be seen with the naked eye anyway. NASA has it covered with a live video
here. The transit will started at 7:15 EST and last a little over seven hours. This event happens only 13 times a century and scientists are using it to study Meecury's exo-atmosphere. Yes, as with exoplanets, such transits in front of a sun are very informative.
