Oftentimes, the X-Men are caught up in very down-to-earth sociopolitical affairs. Therefore, it's easy to forget that sometimes they have to save the world from complete annihilation by cosmic-level threats.
Case in point, the Celestials. A horde of enigmatic space gods who have left one of their own, known as The Dreaming Celestial, standing inert in the outskirts of San Francisco. That is, until Mr. Sinister decided to ape his creator Apocalypse and monkey around with Celestial power for his own ends. This brings the whole horde back to Earth, and it will fall to the X-Men to try and mediate this particular confrontation.
Check out this preview art from Kieron Gillen's Uncanny X-Men #3, featuring pencils by Carlos Pacheco, Paco Diaz and Rodney Buchemi.