Do you fear the LORD?
And there shall be signs in the sun, and in the moon, and in the stars; and upon the earth distress of nations, with perplexity; the sea and the waves roaring;
Men's hearts failing them for fear, and for looking after those things which are coming on the earth: for the powers of heaven shall be shaken.
---LUKE 21.25-26
Asteroid DA14
It cannot hit the earth but it could take out satellites:
http://earthsky.org/space/asteroid-2012-da14-will-pass-very-close-to-earth-in-2013
Big Comet ISON
15 times brighter than the moon:
http://earthsky.org/space/big-sun-diving-comet-ison-might-be-spectacular-in-2013