Here’s another article debunking all the Mayan Calendar nonsense. Niburu is really the easiest to disprove and gets a specific debunking:

“Niburu and Planet X are the same thing, and neither one exists,” Morrison said. “If it were real, astronomers would have been tracking it, and by now it would be the brightest thing in the sky after the moon.

In short, WE’D SEE IT BY NOW. Case closed.