Story highlights Comparable in size to the Golden Gate Bridge, asteroid 231937 or 2001 FO32, will pass within 2,016,351 km of Earth in 2021 The largest asteroid to fly past the Earth in 2021 is set to make a close approach to the planet on March 21. Comparable in size to the Golden Gate Bridge, asteroid 231937 or 2001 FO32, will pass within 2,016,351 km of Earth in 2021. Based on its brightness and the way it reflects light, 2001 FO32 is approximately between 0.767 to 1.714 kilometres in diameter. At Congress's direction, NASA has supported a ground-based program to identify the NEOs larger than one kilometre in diameter. NASA's Jet Propulsion Laboratory has classified 2001 FO32 as a "potentially hazardous asteroid" due to its predicted close pass(es) with Earth.