A small possibility nevertheless remained that, during its 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole estimated to be 800 metres in diameter,[12][13] which would have set up a future impact exactly seven years later on Easter Sunday, April 13, 2036.

[12] During the short time when it had been of greatest concern, Apophis set the record for highest rating ever on the Torino scale, reaching level 4 on December 27, 2004.

[15] The discovery of Apophis in 2004 is rather surprising because it is estimated that an asteroid as big or bigger coming so close to Earth happens only once in 800 years on average.

[17] Preliminary observations by Goldstone radar in January 2013 effectively ruled out the possibility of an Earth impact by Apophis in 2036 (probability less than 1 in a million).

Entering March 2021, six asteroids each had a more notable cumulative Palermo scale rating than Apophis, and none of those has a Torino level above 0.

[24][b] However, Apophis will continue to be a threat possibly for thousands of years until it is removed from being a potentially hazardous object, for instance by passing close to Venus or Mars.

Apophis was discovered on June 19, 2004, by Roy A. Tucker, David J. Tholen, and Fabrizio Bernardi at the Kitt Peak National Observatory.

[citation needed] When first discovered, the object received the provisional designation 2004 MN4, and early news and scientific articles naturally referred to it by that name.

He is the Uncreator, an evil serpent that dwells in the eternal darkness of the Duat and tries to swallow Ra during his nightly passage.

[36] Based on Goldstone and Arecibo radar images taken in 2012–2013, Brozović et al. have estimated that Apophis is an elongated object 450 × 170 metres in size, and that it is bilobed (possibly a contact binary) with a relatively bright surface albedo of 0.35±0.10.

[48] During the 2029 approach, Apophis's brightness will peak at magnitude 3.1,[45] easily visible to the naked eye, with a maximum angular speed of 42° per hour.

[1] Six months after discovery, and shortly after a close approach to Earth on December 21, 2004, the improved orbital estimates led to the prediction of a very close approach on April 13, 2029, by both NASA's automatic Sentry system and NEODyS, a similar automatic program run by the University of Pisa and the University of Valladolid.

The chance that there would be an impact in 2029 was eliminated later in the day of December 27, 2004, as a result of a precovery image that extended the observation arc back to March 2004.

Schweickart also asked NASA to investigate whether a transponder should be placed on the asteroid to enable more accurate tracking of how its orbit is affected by the Yarkovsky effect.

[60] The close approach in 2029 will substantially alter the object's orbit, prompting Jon Giorgini of JPL to say in 2011, "If we get radar ranging in 2013 [the next good opportunity], we should be able to predict the location of 2004 MN4 out to at least 2070.

This means that Apophis will not hit the earth in the coming century, in particular avoiding the keyhole 212.14 km below nominal that would have led to a collision in 2068.

[2] Apophis was the target of an observing campaign by the International Asteroid Warning Network, resulting in the collection of light curves, spectra, and astrometry.

[75] This single detection then allowed the prediction of several more events that would have been unobservable otherwise, including an occultation on April 4, which was observed from New Mexico, again by Venable, alongside others.

[1] As of 2021, the Sentry Risk Table estimated that Apophis would impact Earth with kinetic energy equivalent to 1,200 MT or megatons of TNT.

[17][4] In 2008, the B612 Foundation made estimates of Apophis's path if a 2036 Earth impact were to occur, as part of an effort to develop viable deflection strategies.

[101] The result was a narrow corridor a few kilometres wide, called the "path of risk", extending across southern Russia, across the north Pacific (relatively close to the coastlines of California and Mexico), then right between Nicaragua and Costa Rica, crossing northern Colombia and Venezuela, ending in the Atlantic, just before reaching Africa.

[102] Using the computer simulation tool NEOSim, it was estimated that the hypothetical impact of Apophis in countries such as Colombia and Venezuela, which were in the path of risk, could have more than 10 million casualties.

It will study the asteroid for 18 months and perform a maneuver similar to the one it made during sample collection at Bennu, by approaching the surface and firing its thrusters.

[110][109][clarification needed] SpaceWorks proposed a simple orbiter with only two instruments and a radio beacon at a cost of ~US$140 million, launched aboard a Minotaur IV between 2012 and 2014.

[115][116][clarification needed] Studies by NASA, ESA,[117] and various research groups in addition to the Planetary Society contest teams,[118] have described a number of proposals for deflecting Apophis or similar objects, including gravitational tractor, kinetic impact, and nuclear bomb methods.

On December 30, 2009, Anatoly Perminov, the director of the Russian Federal Space Agency, said in an interview that Roscosmos will also study designs for a possible deflection mission to Apophis.

[119] On August 16, 2011, researchers at China's Tsinghua University proposed launching a mission to knock Apophis onto a safer course using an impactor spacecraft in a retrograde orbit, steered and powered by a solar sail.

[120] 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.

[121] In October 2022, a method of mapping the inside of a potentially problematic asteroid, such as 99942 Apophis, in order to determine the best area for impact was proposed.

[122] In Id Software's video game Rage, the backstory involves the asteroid colliding with Earth on August 23, 2029.