Английская Википедия:2020 CD3

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Шаблон:Short description

Шаблон:Use dmy dates Шаблон:Infobox planet

Шаблон:Mp (also 2020CD3 or CD3 for short)[1][2] is a tiny near-Earth asteroid (or minimoon) that ordinarily orbits the Sun but makes close approaches to the Earth–Moon system, in which it can temporarily enter Earth orbit through temporary satellite capture (TSC). It was discovered at the Mount Lemmon Observatory by astronomers Theodore Pruyne and Kacper Wierzchoś on 15 February 2020, as part of the Mount Lemmon Survey or Catalina Sky Survey. The asteroid's discovery was announced by the Minor Planet Center on 25 February 2020, after subsequent observations confirmed that it was orbiting Earth.

It is the second temporary satellite of Earth discovered in situ, after Шаблон:Mpl, which was discovered in 2006. Based on its nominal trajectory, Шаблон:Mp was captured by Earth around 2016–2017, and escaped Earth's gravitational sphere of influence around 7 May 2020.[3][4][5] Шаблон:Mp will make another close pass to Earth in March 2044, though it will most likely not be captured by Earth due to the greater approach distance.[6][7]

Шаблон:Mp has an absolute magnitude around 32, indicating that it is very small in size. Assuming that Шаблон:Mp has a low albedo characteristic of dark, carbonaceous C-type asteroids, its diameter is probably around Шаблон:Convert.[8][9] Шаблон:Mp is classified as an Arjuna asteroid, a subtype of small Earth-crossing Apollo asteroids that have Earth-like orbits.[3]

Discovery

Файл:2020 CD3 Gemini Color.jpg
Color composite image of Шаблон:Mp obtained by the Gemini Observatory on 24 February 2020[10]

Шаблон:Mp was discovered on 15 February 2020, by astronomers Theodore Pruyne and Kacper Wierzchoś at the Mount Lemmon Observatory. The discovery formed part of the Mount Lemmon Survey designed for discovering near-Earth objects, which is also part of the Catalina Sky Survey conducted at Tucson, Arizona.[11][10] Шаблон:Mp was found as a faint, 20th magnitude object in the constellation of Virgo, located about Шаблон:Cvt from Earth at the time.[12][13]Шаблон:Efn The observed orbital motion of the object suggested that it may be gravitationally bound to Earth, which prompted further observations to secure and determine its motion.[14]

The object's discovery was reported to the Minor Planet Center's Near-Earth Object Confirmation Page (NEOCP), where a preliminary orbit was calculated from additional observations conducted at several observatories.[14] Follow-up observations of Шаблон:Mp spanned six days since its discovery, and the object was formally announced in a Minor Planet Electronic Circular notice issued by the Minor Planet Center on 25 February 2020. No indication of perturbations by solar radiation pressure was observed, and Шаблон:Mp could not be linked to any known artificial object.[11] Although the evidence implied that Шаблон:Mp is most likely a dense, rocky asteroid, the possibility of the object being an artificial object, such as a dead satellite or rocket booster, had not yet been fully ruled out.[15][13]

Precovery images of Шаблон:Mp have been identified back to May 2018.[16]

Nomenclature

Upon discovery, the asteroid was given the temporary internal designation C26FED2.[14][17] After follow up observations confirming the object, it was then given the provisional designation Шаблон:Mp by the Minor Planet Center on 25 February 2020.[11] The provisional designation signifies the object's discovery date and year. The object has not yet been issued a permanent minor planet number by the Minor Planet Center due to its modest observation arc of a couple years and that it has not been observed at enough oppositions.[18]

Orbit

Файл:Animation of 2020 CD3's orbit around Earth.gif
Animation of Шаблон:Mp's orbit around Earth
Шаблон:Legend2Шаблон:·Шаблон:Legend2Шаблон:·Шаблон:Legend2

Prior to the temporary capture of Шаблон:Mp, its heliocentric orbit was probably Earth-crossing, either falling into the categories of an Aten-type orbit (a < 1 AU) or an Apollo-type orbit (a > 1 AU), with the former considered to be more likely.[3]

Temporary capture

Файл:2020CD3.jpg
The orbit of Шаблон:Mp around the Earth. The white band is the orbit of the Moon.
Файл:2020CD3 earth-minimoon-orbits-2015-2020.gif
Trajectory and orbits of Шаблон:Mp around Earth, from 2015 to 2020.Шаблон:Efn

Because Шаблон:Mp has an Earth-like heliocentric orbit, its motion relative to Earth is low, allowing for it to slowly approach the planet and be captured.[3] Nominal orbit solutions for Шаблон:Mp suggest that it was captured by Earth between 2016 and 2017, and left geocentric orbit by May 2020 according to simulations of its orbit.[3][4] The geocentric orbit of Шаблон:Mp is chaotic due to the combined effects of tidal forces from the Sun and Earth as well as repeated close encounters with the Moon.[19][15] The Moon gravitationally perturbs Шаблон:Mp's geocentric orbit, causing it to be unstable. Over the course of Шаблон:Mp's orbit around Earth, repeated close encounters with the Moon leads to ejection from its geocentric orbit as the Moon's perturbations can transfer enough momentum for Шаблон:Mp to escape Earth's gravitational influence.[20][19][21]

Шаблон:Mp's orbit around Earth is highly variable and eccentric, hence predictions of its past trajectory before mid-2017 are uncertain.[9][21] Due to the Yarkovsky effect on small asteroids, the first precovery image being from 2018, and numerous approaches to the Earth and Moon, it is unknown if the asteroid was closer than the Moon on Christmas Day 2015.[22]

Earth Approach Christmas Day 2015?[22]
Date JPL Horizons
nominal geocentric
distance (AU) 		NEODyS
nominal geocentric
distance (AU) 		Find_Orb
nominal geocentric
distance (AU) 		ESA NEOCC
nominal geocentric
distance (AU) 		MPC
nominal geocentric
distance (AU)
2015-Dec-25 Шаблон:Convert Шаблон:Convert Шаблон:Convert Шаблон:Convert Шаблон:Convert

Between September 2017 and February 2020 it made 12 close approaches to Earth,[6] during which time it was never more than Шаблон:Convert from Earth.[23] According to the JPL Small-Body Database, on 15 September 2017 it passed Шаблон:Convert from the Moon.[24] The closest approach to Earth occurred on 4 April 2019, when it approached to a distance of Шаблон:Convert.[24]Шаблон:Efn The final close approach in 2020 occurred on 13 February 2020 at a distance of about Шаблон:Cvt from Earth's surface.[21] The orbital period of Шаблон:Mp around Earth ranged from 70 to 90 days.[21] Шаблон:Mp escaped Earth's Hill sphere at roughly Шаблон:Convert in March 2020[21][25] and returned to solar orbit on 7 May 2020.[3]

Escaping Geocentric Orbit 7 May 2020Шаблон:Efn
(assuming the Earth+Asteroid are the only objects in the Solar System)
Epoch Earth distance[25] Geocentric
eccentricity[5] 		Apogee[5] Orbital period[5]
2020-May-07 Шаблон:Convert 0.9901 Шаблон:Convert Шаблон:Convert
2020-May-08 Шаблон:Convert 1.0347 <math>\infty</math> <math>\infty</math>

Being captured into a temporary orbit around Earth, Шаблон:Mp is a temporarily captured object or a temporary satellite of Earth.[11][26] Шаблон:Mp has also been widely referred to in the media as a "mini-moon" of Earth, due to its small size.[10][8][9][27] Шаблон:Mp is the second known temporary captured object discovered in situ around Earth, with the first being Шаблон:Mpl discovered in 2006.[27] Other objects have also been suspected to have once been temporarily captured, including the small near-Earth asteroid 1991 VG and the bolide DN160822 03.[28][29] Objects that get temporarily captured by Earth are thought to be common, though larger objects over Шаблон:Cvt in diameter are believed to be less likely to be captured by Earth and detected by modern telescopes.[27]

Future approaches

Шаблон:Mp will continue orbiting the Sun and will approach Earth on 20 March 2044, from a distance of Шаблон:Convert.[6] It is unlikely that Шаблон:Mp will be captured by Earth in the March 2044 encounter, as the approach distance is too large for capture[7] and outside of Earth's hill sphere. The next encounter will be August 2061, when it is expected to approach Earth from a nominal distance of Шаблон:Convert.[6] After the 2061 encounter the uncertainties in future encounters become much greater. By 2082 close approaches have a 3-sigma uncertainty of Шаблон:No wrap[24]

The possibility of Шаблон:Mp impacting Earth has been considered by the Jet Propulsion Laboratory's Sentry risk table.[30] JPL's solution accounts for non-gravitational forces[24] as the multi-decade motion of a very small object is greatly affected by solar heating. Being only a few meters in size, an impact by Шаблон:Mp would pose no threat to Earth as it would most likely fragment and disintegrate upon atmospheric entry.[13] With a cumulative impact probability of 2.5%,[30] it is listed as the most likely object to impact Earth, but because of the harmless size of Шаблон:Mp, it is given a Torino Scale rating of 0 and a cumulative Palermo Scale rating of –5.20[30] Within the next 100 years, the date with the highest probability of impact is 9 September 2082, which is estimated to have an impact probability of 0.85% and a negligible Palermo Scale rating of –5.66.[30] JPL Horizon's nominal orbit has the asteroid passing Шаблон:Convert from Earth on 8 October 2082 (29 days after the virtual impactor).[31]

Physical characteristics

Шаблон:Update section Шаблон:Mp is estimated to have an absolute magnitude (H) around 31.7, indicating that it is very small in size.[24] Studies reported in November 2020 have determined that the asteroid is about Шаблон:Convert in diameter.[1][2] The rotation period and albedo of Шаблон:Mp have not been measured due to the limited number of observations.[15] Assuming that the albedo of Шаблон:Mp is similar to those of dark, carbonaceous C-type asteroids, the diameter of Шаблон:Mp is around Шаблон:Cvt, comparable to in size to that of a small car.[9][26] The JPL Sentry risk table estimates Шаблон:Mp to have a mass of Шаблон:Cvt, based on the assumption that the asteroid has a diameter of Шаблон:Cvt.[30]

See also

Notes

Шаблон:Notelist

References

Шаблон:Reflist

External links

Шаблон:Commons category

Шаблон:2020 in space Шаблон:Portal bar Шаблон:Authority control

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  1. ↑ 1,0 1,1 Шаблон:Cite news
  2. ↑ 2,0 2,1 Шаблон:Cite journal
  3. ↑ 3,0 3,1 3,2 3,3 3,4 3,5 Ошибка цитирования Неверный тег <ref>; для сносок Marcos2020 не указан текст
  4. ↑ 4,0 4,1 Ошибка цитирования Неверный тег <ref>; для сносок Bolin2020 не указан текст
  5. ↑ 5,0 5,1 5,2 5,3 Ошибка цитирования Неверный тег <ref>; для сносок Horizons2020-May-07 не указан текст
  6. ↑ 6,0 6,1 6,2 6,3 Ошибка цитирования Неверный тег <ref>; для сносок NEODyS-CA не указан текст
  7. ↑ 7,0 7,1 Ошибка цитирования Неверный тег <ref>; для сносок Koren2020 не указан текст
  8. ↑ 8,0 8,1 Ошибка цитирования Неверный тег <ref>; для сносок Byrd2020 не указан текст
  9. ↑ 9,0 9,1 9,2 9,3 Ошибка цитирования Неверный тег <ref>; для сносок Crane2020 не указан текст
  10. ↑ 10,0 10,1 10,2 Ошибка цитирования Неверный тег <ref>; для сносок Gemini не указан текст
  11. ↑ 11,0 11,1 11,2 11,3 Ошибка цитирования Неверный тег <ref>; для сносок MPEC-2020-D104 не указан текст
  12. ↑ Ошибка цитирования Неверный тег <ref>; для сносок NEODyS-Eph-Dis не указан текст
  13. ↑ 13,0 13,1 13,2 Ошибка цитирования Неверный тег <ref>; для сносок King2020 не указан текст
  14. ↑ 14,0 14,1 14,2 Ошибка цитирования Неверный тег <ref>; для сносок PseudoMPEC не указан текст
  15. ↑ 15,0 15,1 15,2 Ошибка цитирования Неверный тег <ref>; для сносок Howell2020 не указан текст
  16. ↑ Ошибка цитирования Неверный тег <ref>; для сносок MPC-object не указан текст
  17. ↑ Ошибка цитирования Неверный тег <ref>; для сносок NEO-Exchange не указан текст
  18. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Nomenclature не указан текст
  19. ↑ 19,0 19,1 Ошибка цитирования Неверный тег <ref>; для сносок Plait2020 не указан текст
  20. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Baoyin2010 не указан текст
  21. ↑ 21,0 21,1 21,2 21,3 21,4 Ошибка цитирования Неверный тег <ref>; для сносок Naidu2020 не указан текст
  22. ↑ 22,0 22,1 Ошибка цитирования Неверный тег <ref>; для сносок Christmas2015 не указан текст
  23. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Horizons2017-2020 не указан текст
  24. ↑ 24,0 24,1 24,2 24,3 24,4 Ошибка цитирования Неверный тег <ref>; для сносок jpldata не указан текст
  25. ↑ 25,0 25,1 Ошибка цитирования Неверный тег <ref>; для сносок Horizons-Hill не указан текст
  26. ↑ 26,0 26,1 Ошибка цитирования Неверный тег <ref>; для сносок Gough2020 не указан текст
  27. ↑ 27,0 27,1 27,2 Ошибка цитирования Неверный тег <ref>; для сносок Boyle2020 не указан текст
  28. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Tancredi1997 не указан текст
  29. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Gohd2019 не указан текст
  30. ↑ 30,0 30,1 30,2 30,3 30,4 Ошибка цитирования Неверный тег <ref>; для сносок CNEOS не указан текст
  31. ↑ Ошибка цитирования Неверный тег <ref>; для сносок Horizons2082-CA не указан текст
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