On March 23, 1989, an asteroid 1/2 mile in diameter passed within 500,000 miles of Earth. A direct hit would produce a crater 5 to 10 miles in diameter formed from an impact force equal to 20,000 H-bombs.On June 17, 2002, astronomers from the Lincoln Laboratory Near Earth Asteroid Research project (LINEAR) discovered a new Earth-crossing asteroid. Designated 2002 MN, the object is approximately 100 meters across and flew by us on June 14th.
What is most shocking is just how close it came to Earth. This is only the sixth known asteroid to penetrate the Moon's orbit, and by far the biggest. According to Brian G. Marsden (Harvard-Smithsonian Center for Astrophysics), the object came within 120,000 kilometers (0.0008 astronomical unit) of impacting Earth.
Though the exact details of an impact scenario depend on the rock's composition, had it hit Earth the event would have been been "Tunguska-like (in reference to the 1908 explosion in Tunguska which flattened trees over many square miles)," with a force rivaling the largest H-bombs....
