Asteroid (2006 OK3) Just Flew By 'Too Close' by Mitch Battros ECM/ECTV
Asteroid 2006 OK3 did not get the recognition it should have. Just yesterday (July 24th) this 12 meteor diameter rock came within .07 lunar distances from Earth. The distance between the Earth and Moon is approximately 238,857 miles or (384,403 kilometers). This means asteroid 2006 OK3 came within 167,212 miles from a collision with our home. In the astronomical world this is a razors hair in distance. If this rock would have been just a bit larger, all hell would have broke loose.
The IAU Minor Planet Center announced this intruder just 3 days ago on Saturday July 22nd. Asteroid 2006 OK3 was discovered by the Siding Spring Survey in Australia at 1414 UT and was confirmed by that facility alone, which followed it for the next 31 minutes.
As asteroids go, "small" is defined as having an absolute magnitude (brightness) which converts very roughly to a diameter under 135 meters. No matter how close they come to the Earth, the astronomical community does not classify such objects as "potentially hazardous." However, as demonstrated by the mile wide (1.6 km.) Barringer Crater in Arizona, blasted out by a "small" asteroid some 50,000 years ago, there are asteroids too small to be labeled "potentially hazardous" that actually could cause severe local damage. These are sometimes called "Tunguska-class objects" (TCOs), after the 1908 event probably caused by a comet fragment or asteroid too small to be classified today as hazardous but packing enough wallop to flatten a Siberian forest area the size of a large city.
In December 2005 the NEO division (near earth object) changed its main risk page to classify "Objects too small to result in heavy damage on the ground" as having "absolute magnitude > 25," which corresponds to perhaps 35 meters wide. And JPL two months earlier started flagging (with a blue background) risk-listed objects of an estimated diameter 50 meters or less as "not likely to cause significant damage in the event of an impact, although impact damage does depend heavily upon the specific (and usually unknown) physical properties of the object in question."
Small asteroids that come close enough to Earth to be seen have significant potential for scientific study today, and for exploration and exploitation in the future. They present a sampling of distant asteroid populations and a few may be remnants of the event that created the Earth-Moon system.
Some of these objects are discovered while close to Earth moving across the sky quite quickly, when they are called "FMOs" or "VFMOs" (very fast moving objects). The discovery and follow-up tracking of asteroids with represents some of the most difficult and very best observing work being done today by amateur and professional astronomers around the world.