NASA: Mystery object is 54-year-old rocket, not asteroidWashington, Mar 22: The largest asteroid called 2001 FO32, to pass by Earth this year has made its closest approach, posing no threat of a cataclysmic collision but provided an opportunity for astronomers to get a more precise understanding of the asteroid's size and albedo (i.e. how bright, or reflective, its surface is), and a rough idea of its composition.
The asteroid was two million kilometres (1.25 million miles) away at its nearest, according to NASA-more than five times the distance between the Earth and the Moon but still close enough to be classified as a "potentially hazardous asteroid".
NASA: Mystery object is 54-year-old rocket, not asteroid
The reason for the asteroid's unusually speedy close approach is its highly inclined and elongated (or eccentric) orbit around the Sun, an orbit that is tilted 39 degrees to Earth's orbital plane. This orbit takes the asteroid closer to the Sun than Mercury and twice as far from the Sun as Mars.
Asteroid 2001 FO32 was discovered in March 2001 by the Lincoln Near-Earth Asteroid Research (LINEAR) program in Socorro, New Mexico, and had been estimated, based on optical measurements, to be roughly 3,000 feet (1 kilometer) wide.
The last notably large asteroid close approach was that of 1998 OR2 on April 29, 2020. While 2001 FO32 is somewhat smaller than 1998 OR2, it will be three times nearer to Earth.
Near-Earth objects: How near is too near?
According to NASA, a Near-Earth Object (NEO) is generally defined as an asteroid or comet that approaches our planet less than 1.3 times the distance from Earth to the Sun (the Earth-Sun distance is about 93 million miles). Most NEOs pose no peril at all. It's the small percentage of Potentially Hazardous Asteroids that draws extra scrutiny. These objects are defined as those that approach Earth at less than half the Earth-Sun distance.