Designated 2010 ST3, this asteroid will come within four million miles of Earth in October and there's a very slight chance that it will hit us in 2098. Were that to come to pass, at 150 feet across, the impact would have the effect of a 20 megaton bomb. However, the impact is highly unlikely. The Earth and 2010 ST3 occupy the same potential volume of space in 2098, but that volume is huge. As time goes on and projections get more precise, it's likely that we'll find that the Earth will end up outside of the asteroid's path.