Dave Tholen and collaborators have detected light from the sun is moving the 300 meter near-Earth asteroid Apophis by 170 meters per year. This acceleration means that Apophis might hit the earth in 2068.
Detailed analysis on the next close pass in 2029 will determine if Apophis is a risk.
The Sentry Risk Table estimates that Apophis would impact Earth with kinetic energy equivalent to 1,200 megatons of TNT.
The highest probability of impact is on April 12, 2068 and the odds of an impact on that date, as calculated by the JPL Sentry risk table using a March 2016 solution, are 1 in 150,000. The calculations are that it should miss the Earth by 150 million kilometers. The acceleration should only shift the asteroid by about 122 kilometers.
Assuming Apophis is a 370-meter-wide (1,210 ft) stony asteroid with a density of 3,000 kg/m3, then if it were to impact into sedimentary rock, Apophis would create a 5.1-kilometer (17,000 ft) impact crater.
A deep-water impact in the Atlantic or Pacific oceans would produce an incoherent short-range tsunami with a potential destructive radius (inundation height of about 2 meters) of roughly 1,000 kilometers (620 mi) for most of North America, Brazil and Africa, 3,000 km (1,900 mi) for Japan and 4,500 km (2,800 mi) for some areas in Hawaii.
SOURCES- Wikipedia, University of Hawaiʻi Institute for Astronomy, Sentry Risk Table, B612 Foundation
Written By Brian Wang, Nextbigfuture.com