"We know the time that the object is going to be closest within seconds, and the distance is known within hundreds of kilometers", Davide Farnocchia, a mathematician at NASA's Near-Earth Object programme, said by telephone on Tuesday.
This closeness will not pose any threat to Earth as NASA ruled out the chances of the 2,000 foot wide space rock hitting our planet.
First discovered three years ago, the asteroid is believed to be around 650m in size with a surface about twice as reflective as that of the moon.
Just to show how frequent these objects comes within a short distance from Earth, the comet PanSTARRS will also make its closest approach to Earth on 19 April at a very safe distance of 175m km. That asteroid came within four lunar distances from Earth.
That's still the closest an asteroid of sizeable proportions has zipped past the planet since 2004, and will be the largest to for another 10 years, according to NASA.
A giant, peanut-shaped asteroid will come into "potentially hazardous" close contact with Earth on Wednesday. It only means that 2014-JO25 will be five times closer to Earth than the Moon. At that time, 1999 AN10 asteroid (800-meter-wide) will cruise by Earth at one lunar distance. The asteroid is visible through a small optical telescope at least two nights before it moves out of range. According to NASA, the space rock will pass Earth safely and there is no danger of any collision.
Although not fatal, some experts say that smaller and less risky asteroids do pass the Earth at even nearer distances than "the rock".
However, in astronomical measurements, the April 19 asteroid's trajectory - zipping about 1.1 million miles away from the Earth - is considered a close call.
Radar studies are scheduled at NASA's Goldstone Solar System Radar in California and the National Science Foundation's Arecibo Observatory in Puerto Rico.