On June 27 the asteroid should fly 7,500 miles above the Earth's surface. The asteroid, named 2011 MD, was discovered last Wednesday by a pair of roboti telescopes in New Mexico that constantly scan the skies. NASA estimates that an object this size comes this close to Earth on an average of every six years.
NASA said for several hours prior to its closest approach, 2011 MD will be visible in moderately large amateur telescopes.
Of the thousands of objects discovered by NASA, approximately 827 are asteroids with a diameter of approximately a half-mile or larger. They're classified as Potential Hazardous Asteroid. NASA is planning to launch a probe to visit one of the dangerous objects before the asteroid makes its way near the Earth.