Apophis asteroid Wikipedia Page:
“99942 Apophis (/əˈpɒfɪs/, previously known by its provisional designation 2004 MN4) is anear-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. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth or the Moon in 2029. However, until 2006, a possibility remained that during the 2029 close encounter with Earth, Apophis would pass through agravitational keyhole, a small region no more than about 965 kilometres (600 miles) wide,[8][9] 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. By 2008, the keyhole had been determined to be less than 1 km wide.[8]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.[10]
The diameter of Apophis is, as of the most recent 2013 observations, approximately 325 metres (1,066 ft).[2] Preliminary observations by Goldstone radar in January 2013 effectively ruled out the possibility of an Earth impact by Apophis in 2036.[11] By May 6, 2013 (April 15, 2013 observation arc), the probability of an impact on April 13, 2036 had been eliminated.[3] 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.[3] As of December 2016, of objects not recently observed, there were about five asteroids with a more notable Palermo Technical Impact Hazard Scale than Apophis.[12] On average, an asteroid the size of Apophis (325 metres) can be expected to impact Earth about every 80,000 years.[13]“
(Other pages: Discovery and naming, Physical characteristics, Orbit, Possible impact effects…)
https://en.m.wikipedia.org/wiki/99942_Apophis
