Nothing currently.
Some of the most popular space-based threats to the Earth and
mankind focus on Planet X wiping most life off the planet,
meteorite impacts, black holes, killer solar flares, Gamma Ray Bursts from star
systems, a rapid ice age and a polar (magnetic) shift. There is so much evidence
against these things happening in 2012, it's shocking just how much of a
following they have generated. Each of the above "threats" needs their own
devoted article as to why there is no hard evidence to support the
hype.