A three-mile-wide asteroid will sail past Earth on Friday — the largest object to make a close-encounter, albeit 4.4 million miles away, since NASA began tracking the events in the 1990s.

Asteroid Florence was named after modern nursing founder Florence Nightingale, and was discovered in 1981 by astronomer Schelte Bus from the Siding Spring Observatory in Australia.

"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.