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Revision as of 09:59, 19 February 2016
99942 Apophis (/əˈpɒfɪs/, previously known by its provisional designation 2004 MN4) is a near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a probability of up to 2.7% that it would hit Earth on April 13, 2029.
Size
The diameter of Apophis is, as of the most recent 2013 observations, approximately 325 metres (1,066 ft).
Earth impact predictions
Additional observations provided improved predictions that eliminated the possibility of an impact on Earth or the Moon in 2029.
However, a possibility remained that during the 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole, a small region no more than about 800 m (~0.5 mi) wide, that would set up a future impact exactly seven years later, on April 13, 2036.
This possibility kept it at Level 1 on the Torino impact hazard scale until August 2006, when the probability that Apophis would pass through the keyhole was determined to be very small.
During the short time when it had been of greatest concern, Apophis set the record for highest rating on the Torino scale, reaching level 4.
Preliminary observations by Goldstone radar in January 2013 effectively ruled out the possibility of an Earth impact by Apophis in 2036.
By May 6, 2013 (April 15, 2013 observation arc), the probability of an impact on April 13, 2036 had been eliminated. As of October 8, 2014, using observations through February 26, 2014, the odds of an impact on April 12, 2068, as calculated by the JPL Sentry risk table is (1 in 149,000).
Deflection strategies
On February 15, 2016, Sabit Saitgarayev, of the Makeyev Rocket Design Bureau, announced intentions to use Russian ICBMs to target relatively small near-Earth objects.
Although the report stated that likely targets would be between the 20 to 50 meters in size, it was also stated that 99942 Apophis would be an object subject to tests by the program.
See also
External links
- 99942 Apophis @ Wikipedia
