Astronomers anticipate the approach of a prominent-sized asteroid as it passes Earth just beyond the orbit of the moon.
Discovered by Lincoln Laboratory Near Earth Asteroid Research (LINEAR) on December 10, 2004, Asteroid 2004 XP14, is due to come uncomfortably close to Earth during the early hours of Monday, July 3, 2006.
The LINEAR project, funded by the United States Air Force and NASA, uses technology that was developed to monitor satellites orbiting the Earth, in an attempt to locate and record potential cosmic threats to our planet. To date, the LINEAR project has confirmed 1622 Near Earth Objects (NEOs), which also includes comets with a close approach orbit to the Earth. The greatest current potential impact risk, at an estimated diameter of 300 metres, is asteroid 99942 Apophis (2004 MN4) when it approaches Earth in April of 2036. The probability of 99942 Apophis impacting the Earth is 0.0026% or 1 in 38,000.
Believed to be 600 metres or more in diameter, Asteroid 2004 XP14 was originally thought to be an impact threat, but further studies of its orbit later revealed the big rock is not an immediate danger to the Earth. Classed as a PHA (Potentially Hazardous Asteroid), 2004 XP14 is one of 796 within this classification, which is defined as an asteroid with a Minimum Orbit Intersection Distance (MOID) with the Earth of 0.05 AU or less, and an absolute magnitude of 22.0 or brighter.
The asteroid will pass just beyond the orbit of the moon at 1.1 LD (lunar distance from Earth) and is expected to reach an absolute magnitude of 12, so amateur and professional astronomers will be readying their telescopes in order to catch a glimpse of the fly-by. It will be traveling at a relative velocity of 17.41 kilometres per second.
At a distance of 1.7 LD, the most recent close approach by an NEO was only a few days ago on June 28th 2006, by 2006 MB14, but at an estimated diameter of 24-53 metres, it was a mere pebble compared to 2004 XP14. NEOs at such distances are somewhat rare. The next known asteroid expected to pass at a comparable distance of 1.4 LD, is 2005 YU55 in November of 2011; and then another, 1999 AN10, in August of 2027 at a distance of 1.0 LD. NASA reports that asteroid 1999 AN10 is at least 1 kilometre in diameter, and with the projected distance of this asteroid relative to the moon, we can certainly anticipate apocalyptic stories to accompany its approach.