The gigantic missile thought to measure almost a mile across will brush closer than previous monsters which have sparked a global panic.
Worried astronomers warned 1999 FN53, which is an eighth of the size of Mount Everest, will skim the Earth in TWO DAYS.
A collision would be nothing short of catastrophic triggering mass destruction, earthquakes and global extinction.
The monster is more than TEN TIMES bigger than other meteorites currently visible on NASA’s Near Earth Object radar.
It is also double the size of the gargantuan 2014-YB35 which had astronomers around the world watching the skies in March.
Experts warn a collision would trigger an explosion similar to millions of megatons of TNT and would be capable of killing 1.5 billion people.
It would be far more destructive than the 1908 Tunguska Event which saw a 50-metre lump of extraterrestrial rock crash into Siberia.
It flattened around 80 million trees and sent a shock wave across Russia measuring five on the Richter scale.
The event is held by scientists as a benchmark for the catastrophic consequence of an asteroid impact with earth.
The gigantic lump of rock is travelling faster than 30,000 mph and will brush terrifyingly close to Earth on Thursday.