Okay...so it is the big day. I'm actually typing this on Tuesday, the 9th of September.  So if you are reading this then the earth wasn't destroyed...err...well the internet is still intact and so is whatever spaceship you've managed to stitch together. The above clip is the CERN lab explained [purpose, history, hubbub, etc.] in 3 minutes.

The European Organization for Nuclear Research known as CERN is the world's largest particle physics laboratory, situated in the northwest suburbs of Geneva on the Franco-Swiss border. The Large Hadron Collider (LHC) will begin operations soon. On September 10th, the most sophisticated particle accelerator will go online, injecting the first circulation of accelerated particles. Actual experiments involving collisions will occur once scientists are satisfied the LHC is fully optimized and calibration is complete. The LHC has been undergoing "cool-down" for some time, ensuring the LHC's eight sectors are approaching the 1.9K (-271°C) operational temperature (that is 1.9 degrees above absolute zero). All going well, on September 10th, the first beam will be accelerated to an energy of 450 GeV (0.45 TeV), the preliminary step on the path to attaining particle energies of 5 TeV, a record breaking target

After the jump is a clip if things went horribly awry today...

Below is an estimation of what could have happened had a large amount of black holes adopted each other and thus swallowed the Earth up.

The BBC has built quiet the website for the LHC check it out here