Kitt Peak Observations Help Lower Asteroid Risk Estimate

Apophis

Image Credit: NASA Photo

Apophis, an asteroid discovered on 19 June 2004 during observations at Kitt Peak National Observatory, caused a media stir when an estimate from NASA was released on 23 December 2004 of there being a one-in-300 chance of hitting the Earth in 2029. This put it at a Level 2 on the Torino Scale. The next day, an update stated:

December 24 Update: 2004 MN4 is now being tracked very carefully by many astronmers around the world, and we continue to update our risk analysis for this object. Today’s impact monitoring results indicate that the impact probability for April 13, 2029 has risen to about 1.6%, which for an object of this size corresponds to a rating of 4 on the ten-point Torino Scale. Nevertheless, the odds against impact are still high, about 60 to 1…

Over time, the risk level has gradually been lowered as additional measurements have been made. As early as 3 February 2005, NASA ruled out a collision in 2029 (Friday the 13th, April), when it would come no closer than 36,350 kilometers above the Earth’s surface. However, this still left open a possible encounter in 2036.

Now, observations made by the 2.3 meter (90-inch) Bok telescope at the Kitt Peak National Observatory near Tucson, Arizona, along with measurements from the Arecibo Observatory on the island of Puerto Rico have been combined with observations by Dave Tholen and collaborators at the University of Hawaii‘s Institute for Astronomy in Manoa. The previous estimate for 2036 was one-in-45,000, The new refined estimate is one-in-250,000 (6 times less likely).

NASA now reports that:

…the asteroid is expected to make a record-setting — but harmless — close approach to Earth on Friday, April 13, 2029, when it comes no closer than 29,450 kilometers (18,300 miles) above Earth’s surface.

See Eric Berger’s Blog on Preparedness for NEO Impacts on the Earth.

Also, its a crowded Solar System.