For a decade now astronomers have been tracking the progress of a dense gas cloud called G2 which now is rapidly approaching the Galactic center on a very eccentric elliptical orbit (eccentricity ~ 0.95) and is estimated to reach pericenter (the point of closest approach) around the beginning of July 2013. Tidal forces have already been observed to stretch the cloud and these forces will become increasingly strong over the next 9 months as the cloud approaches orbit pericenter at which point it is thought that they will be strong enough to completely rip the cloud apart. At this point the dispersed cloud is expected to be gravitationally drawn into the Galactic core with the consequent release of a large amount of energy in the form of cosmic rays and gamma ray emission.
I have been asked by several people whether the cloud’s consumption on this 2013 date might produce a Galactic superwave which would be reaching our solar system on that same date (due to the ability of the cosmic rays to travel straight toward us at close to the speed of light) and produce a major solar system cataclysm; e.g. see the forum comment by psychiceyes. Indeed, due to the ending of the Mayan calendar cycle on December 21, 2012, there are many who expect an end of world scenario or consciousness transition event. In fact, some groups have built shelters in the heart of Australia and South Africa with this expectation in mind.
To read more on this go to the Superwave Forum.