“It seems prudent to mount efforts to discover and study these objects, to characterise their sizes, compositions and structures and to keep an eye upon their future trajectories.”
Asteroid XO1 is estimated to measure somewhere in the range of 108.3ft to 242.8ft (33m to 74m) across.
An asteroid this big would survive the descent through the atmosphere and slam into the ground with brute force.
At the upper end of NASA’s estimate, Asteroid XO1 is comparable in width to the wingspan of a Boeing 747.
The asteroid is also almost as tall as the Statue of Liberty in New York, US.