In 2004, astronomers at Kitt Peak Observatory in Arizona, USA discovered a near earth asteroid, dubiously named 99942 Apophis. The asteroid is about 200 m across in diameter. It became famous for being an asteroid with a rating of 4 on the Torino Imapact Hazard scale. Since 2006, the asteroid had been demoted to 0. However recent studies into the asteroid’s orbit has questioned the accuracy of this rating. Scientist in Russia think that there is a very real chance this asteroid will impact earth in 2036.
This observation has been refuted by NASA. According to Donald Yeomans, director of NASA’s near earth objects office claims that the probability of impact is currently 1/250,000.
Apophis will come within 5 earth radii distance of the earth in 2029. However if the asteroid passes within a region of space called the “keyhole” during this period, the orbit might change enough to cause impact with earth.
The predicted date of impact is April 13, 2036.
Apophis carries a massive Kinetic energy of 5.1e+02 Mega Tonnes of TNT equivalent. To put numbers in perspective, the Hiroshima nuclear bomb had a 20 Kilo tonnes yield.
However from preliminary calculations we did based on this article, a Apophis class asteroid will create a 4 Km wide impact crater on a direct hit.
Predicted possible impact locations of Apophis