2012 and a comet/asterioid?

Now some say its a comet, some say its an asteroid? Some say the government/nasa is hiding this? true? Some say it would be visible by now, some say it doesn't need to be visible by now? I read one guy's blog that said that this comet/asteroid doesn't need to be visible until like 137 some days before it reaches if compared to the speed of haley's comet? He said if it had the speed of haley's comet then it would only be visible 137 days or so until we could see it? Would we know if something was happening soon? Some say that a certain spot in google sky is blocked out? is that true? What are all the explanations for these? What's be the truth? Could something just appear out of no where soon? truth or myth? explanations?