"While many known asteroids have passed by closer to Earth than Florence . . . all of those were estimated to be smaller," Paul Chodas, manager of NASA's Center for Near-Earth Object Studies in Pasadena, California, told spaceflightinsider.com.
Earlier this year, a 10-foot-wide, near-earth object (NEO) passed by at an altitude of just 9,000 miles — within the band of geostationary satellites at 22,300 miles, the outlet reported – and was detected just six hours before its closest approach.