Close Call

May 20, 1993 — On this day, a small asteroid known as 1993 KA2 passed within 93,000 miles of Earth, less than half the distance to the Moon. The object, estimated to be between 13 and 30 feet wide, wasn't discovered until after it had already flown past the planet.

While an asteroid that size would likely break apart in the atmosphere before reaching the ground, it could still produce a powerful airburst capable of causing local damage.

NASA currently tracks thousands of Near-Earth Objects (NEOs) and maintains special watch lists for larger Potentially Hazardous Objects (PHOs) whose orbits bring them relatively close to Earth. At present, no known asteroid poses an impact threat in the foreseeable future—but the 1993 flyby was a reminder that space can still surprise us.