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This is a list of asteroids that have impacted Earth after discovery and orbit calculation that predicted the impact in advance. As of December 2024 [update] , all of the asteroids with predicted impacts were under 5 m (16 ft) in size that were discovered just hours before impact, and burned up in the atmosphere as meteors .
99942 Apophis (provisional designation 2004 MN 4) is a near-Earth asteroid and a potentially hazardous object, 450 metres (1,480 ft) by 170 metres (560 ft) in size, [3] that caused a brief period of concern in December 2004 when initial observations indicated a probability of 2.7% that it would hit Earth on Friday, April 13, 2029.
The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, discovered by German astronomer Karl Reinmuth in the 1930s. They are Earth-crossing asteroids that have an orbital semi-major axis greater than that of the Earth (a > 1 AU ) but perihelion distances less than the Earth's aphelion distance (q < 1.017 AU).
Among the numbered minor planets with an unambiguous period solution are (459872) 2014 EK 24, a 60-meter sized stony NEO with a period of 352 seconds, as well as (335433) 2005 UW 163 and (60716) 2000 GD 65, two main-belt asteroids, with a diameter of 0.86 and 2.25 kilometers and a period of 1.29 and 1.95 hours, respectively (see full list).
Asteroids are classified by their characteristic emission spectra, with the majority falling into three main groups: C-type, M-type, and S-type. These describe carbonaceous (carbon-rich), metallic, and silicaceous (stony) compositions, respectively. The physical composition of asteroids is varied and in most cases poorly understood.
A new category of asteroids was thus created, the Atens. As of 2017, the group consists of more than 1,200 numbered members. As of 2017, the group consists of more than 1,200 numbered members. Other groups of near-Earth objects (NEOs) are the Apollo and Amor asteroids, which are both significantly larger than the Atens, while the Atira ...
3753 Cruithne is a Q-type, Aten asteroid in orbit around the Sun in 1:1 orbital resonance with Earth, making it a co-orbital object.It is an asteroid that, relative to Earth, orbits the Sun in a bean-shaped orbit that effectively describes a horseshoe, and that can change into a quasi-satellite orbit. [3]
Aten asteroids account for only about 7.4% of the known near-Earth asteroid population. [4] Many more Apollo-class asteroids are known than Aten-class asteroids, possibly because of the sampling bias. The shortest semi-major axis for any known Aten asteroid is 0.580 AU, for object 2016 XK 24. [3]