... Will Earth break up 2004 MN4? ... F or a few days at the end of December, an asteroid named 2004 MN4 looked like it might be Earth's biggest impact threat. ... Although a miss in 2029 is virtually certain, if MN4 survives its Earth flyby, astronomers cannot rule out potential collisions in the 2030's. Therefore, 2004 MN4 still holds at 1 on the Torino impact hazard scale, a classification designed to quantify the impact risk of near-Earth asteroids (similar to the Ritcher scale for earthquakes). ...