The Mayan calender end of the world comet! ;-)
I am quite disappointed that astronomers are STILL pushing the completely erroneous idea that comets have “ice” that melts and evaporates to form the tail... After all the fly-bys, contacts and even destructive impact testing we have done on comets and found NO ICE! None, nada. Nil!
Comets flare in relation to the electrical activity of the sun and the solar wind. Cometary tails and comas are plasma phenomena and are electrical in nature. They exhibit all of the characteristics of plasmas and can even be demonstrated in the laboratory, simulated in computer modeling using plasma math, and photographs of comets show they are indistinguishable from any normal asteroid, except in orbital dynamics.
They are NOT dirty snowballs. They are charged bodies of rock, emitting electrons as they enter a differently charged area of the solar system, electrically machining the surface and carrying charged ions away. The solar wind repels these like charged ions away from the sun, creating the tail.
The universe is driven by electromagnetism, a force that is 39 orders of magnitude more powerful than gravity.