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The asteroid, known as 2014 JO25, was discovered in May 2014 by astronomers at the Catalina Sky Survey near Tucson, Arizona -- a project of NASA's NEO (near-Earth object) Observations Programme in collaboration with the University of Arizona.
The surface of the asteroid is about twice as reflective as that of the moon, according to the scientists.
It is predicted to brighten to about magnitude 11, when it could be visible in small optical telescopes for one or two nights before it fades as the distance from Earth rapidly increases.
"Small asteroids pass within this distance of Earth several times each week but this upcoming close approach is the closest by any known asteroid of this size, or larger, since asteroid Toutatis, a five-kilometre asteroid, which approached within about four lunar distances in September 2004," NASA said in a statement on Friday.
The April 19 encounter provides an outstanding opportunity to study this asteroid and astronomers plan to observe it with telescopes around the world to learn as much about it as possible.
Also on April 19, the comet PanSTARRS (C/2015 ER61) will make its closest approach to Earth, at a very safe distance of 175 million km, NASA said.