2014 AA was a small

Apollo Apollo is one of the Twelve Olympians, Olympian deities in Ancient Greek religion, ancient Greek and Ancient Roman religion, Roman religion and Greek mythology, Greek and Roman mythology. Apollo has been recognized as a god of archery, mu ...

near-Earth asteroid A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit aro ...

roughly 2–4 meters in diameter that

struck Struck is a surname. Notable people with the surname include: *Adolf Struck Adolf Hermann Struck (1877–1911) was a German sightseer and writer. He is known for his Travel literature, travelogue ''Makedonische Fahrten'' and for surveying the ...

Earth on 2 January 2014. It was discovered on 1 January 2014 by Richard Kowalski at the

Mount Lemmon Survey Mount Lemmon Survey (MLS) is a part of the Catalina Sky Survey with observatory code G96. MLS uses a cassegrain reflector telescope (with 10560x10560-pixel camera at the f/1.6 prime focus, for a five square degree field of view) operated by ...

at an

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of 19 using a

reflecting telescope A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternati ...

at Mount Lemmon Observatory. 2014 AA was only observed over a short observation arc of about 70 minutes, and entered Earth's atmosphere about 21 hours after discovery. Nonetheless, it remains one of only a few asteroids observed before impact (see Asteroid impact prediction).

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Using a poorly determined orbit, the

JPL Small-Body Database The JPL Small-Body Database (SBDB) is an astronomy database about small Solar System bodies. It is maintained by Jet Propulsion Laboratory (JPL) and NASA and provides data for all known asteroids and several comets, including orbital parameters and ...

listed a 3-sigma solution with impact occurring around 2 January 2014 02:33 UT ± 1 hour and 5 minutes. The

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Funct ...

listed impact as occurring around 2 January 2014 05:00 UT ± 10 hours. Independent calculations by Bill Gray, the Minor Planet Center and Steve Chesley at the

Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center (FFRDC) in La Cañada Flintridge, California, Crescenta Valley, United States. Founded in 1936 by Cali ...

verified that impact was virtually certain. It entered the atmosphere going about 11.7 km/s with respect to Earth. The impactor would have been roughly the size of , which exploded above the

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in Sudan on 7 October 2008. Calculations by Chesley suggest the impactor fell somewhere on an arc extending from Central America to East Africa, with a best-fit location just off the coast of West Africa. Calculations by Pasquale Tricarico using the nominal orbit show that 2014 AA entered Earth's shadow cone approximately 40 minutes before entering the atmosphere.

Infrasound Infrasound, sometimes referred to as low frequency sound or incorrectly subsonic (subsonic being a descriptor for "less than the speed of sound"), describes sound waves with a Audio frequency, frequency below the lower limit of human audibility ...

was detected by three stations of the Comprehensive Nuclear-Test-Ban Treaty Organization. Peter Brown and Petrus Jenniskens located weak signals from infrasound stations in Bolivia, Brazil and Bermuda. 2014 AA entered Earth's atmosphere around 03:06 ± 5 min UT, 3,000 km from

Caracas Caracas ( , ), officially Santiago de León de Caracas (CCS), is the capital and largest city of Venezuela, and the center of the Metropolitan Region of Caracas (or Greater Caracas). Caracas is located along the Guaire River in the northern p ...

, Venezuela, far from any landmass. No ships or planes reported witnessing the event. A recalculation of the impact parameters of this meteor based on infrasound recordings puts it in the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

about 1900 km (1030 nautical miles) east of

Port of Spain Port of Spain ( ; Trinidadian and Tobagonian English, Trinidadian English: ''Port ah Spain'' ) is the capital and chief port of Trinidad and Tobago. With a municipal population of 49,867 (2017), an urban population of 81,142 and a transient dail ...

Trinidad Trinidad is the larger, more populous island of the Republic of Trinidad and Tobago, the country. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is the southernmost island in ...

, at a longitude of impact of nearly 44º west and a latitude of 11º north, the impact time being 2456659.618 JD UTC. Extensive numerical simulations indicate that, prior to impact, 2014 AA was subjected to a number of secular resonances and it may have followed a path similar to those of the NEOs , , , and ; NEOs in this transient group experience close encounters with the Earth-Moon system at perihelion and Mars at aphelion and could be a dynamical family.

Other discoveries

Kowalski previously discovered , the first asteroid discovered before Earth's impact, using the same telescope in October 2008. There are about a

billion Billion is a word for a large number, and it has two distinct definitions: * 1,000,000,000, i.e. one thousand million, or (ten to the ninth power), as defined on the short scale. This is now the most common sense of the word in all varieties of ...

near-Earth objects in the size range of 2014 AA, and impacts of comparably-sized objects occur several times each year. Several years later, 2018 LA was also discovered by the Mount Lemmon Survey, and ended up impacting Earth in southern

Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...

in June 2018.

References

External links

The atmospheric impact trajectory of asteroid 2014 AA

arXiv arXiv (pronounced as "archive"—the X represents the Chi (letter), Greek letter chi ⟨χ⟩) is an open-access repository of electronic preprints and postprints (known as e-prints) approved for posting after moderation, but not Scholarly pee ...

13 January 2016
Two maps of the possible impact region
(Yahoo groups / Project Pluto)
2014 AA – New Year’s Earth impactor
( Carl W. Hergenrother) * * {{DEFAULTSORT:2014 AA # Minor planet object articles (unnumbered) Discoveries by Richard Kowalski January 2014 Predicted impact events 20140102 20140101 2014 in outer space Modern Earth impact events

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Other discoveries

See also

References

External links