2020 CD3

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Template:Short description

Template:Use dmy dates Template:Infobox planet

Template:Mp (also 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 Template:Mpl, which was discovered in 2006. Based on its nominal trajectory, Template:Mp was captured by Earth around 2016–2017, and escaped Earth's gravitational sphere of influence around 7 May 2020.[3][4][5] Template: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]

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

Discovery

Colour composite image of Template:Mp obtained by the Gemini Observatory on 24 February 2020[10]

Template: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] Template:Mp was found as a faint, 20th magnitude object in the constellation of Virgo, located about Template:Cvt from Earth at the time.[12][13]Template: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 Template: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 Template:Mp could not be linked to any known artificial object.[11] Although the evidence implied that Template: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 Template: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 Template: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

Animation of Template:Mp's orbit around Earth
Template:Legend2Template:·Template:Legend2Template:·Template:Legend2

Prior to the temporary capture of Template: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

The orbit of Template:Mp around the Earth. The white band is the orbit of the Moon.
Trajectory and orbits of Template:Mp around Earth, from 2015 to 2020Template:Efn

Because Template: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 Template: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 Template: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 Template:Mp's geocentric orbit, causing it to be unstable. Over the course of Template: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 Template:Mp to escape Earth's gravitational influence.[20][19][21]

Template: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 Template:Convert Template:Convert Template:Convert Template:Convert Template:Convert

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

Escaping geocentric orbit 7 May 2020Template: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 Template:Convert 0.9901 Template:Convert Template:Convert
2020-May-08 Template:Convert 1.0347 ∞ ∞

Being captured into a temporary orbit around Earth, Template:Mp is a temporarily captured object or a temporary satellite of Earth.[11][26] Template: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] Template:Mp is the second known temporary captured object discovered in situ around Earth, with the first being Template: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 Template:Cvt in diameter are believed to be less likely to be captured by Earth and detected by modern telescopes.[27]

Future approaches

Template:Mp will continue orbiting the Sun and will approach Earth on 20 March 2044, from a distance of Template:Convert.[6] It is unlikely that Template: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 Template:Convert.[6] After the 2061 encounter the uncertainties in future encounters become much greater. By 2082 close approaches have a 3-sigma uncertainty of Template:No wrap[24]

The possibility of Template: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 Template: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 Template: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 Template:Convert from Earth on 8 October 2082 (29 days after the virtual impactor).[31]

Physical characteristics

Template:Update section Template: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 Template:Convert in diameter.[1][2] The rotation period and albedo of Template:Mp have not been measured due to the limited number of observations.[15] Assuming that the albedo of Template:Mp is similar to those of dark, carbonaceous C-type asteroids, the diameter of Template:Mp is around Template:Cvt, comparable to in size to that of a small car.[9][26] The JPL Sentry risk table estimates Template:Mp to have a mass of Template:Cvt, based on the assumption that the asteroid has a diameter of Template:Cvt.[30]

See also

Notes

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References

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

  1. ↑ 1.0 1.1 Template:Cite news
  2. ↑ 2.0 2.1 Template:Cite journal
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Cite error: Invalid <ref> tag; no text was provided for refs named Marcos2020
  4. ↑ 4.0 4.1 Cite error: Invalid <ref> tag; no text was provided for refs named Bolin2020
  5. ↑ 5.0 5.1 5.2 5.3 Cite error: Invalid <ref> tag; no text was provided for refs named Horizons2020-May-07
  6. ↑ 6.0 6.1 6.2 6.3 Cite error: Invalid <ref> tag; no text was provided for refs named NEODyS-CA
  7. ↑ 7.0 7.1 Cite error: Invalid <ref> tag; no text was provided for refs named Koren2020
  8. ↑ 8.0 8.1 Cite error: Invalid <ref> tag; no text was provided for refs named Byrd2020
  9. ↑ 9.0 9.1 9.2 9.3 Cite error: Invalid <ref> tag; no text was provided for refs named Crane2020
  10. ↑ 10.0 10.1 10.2 Cite error: Invalid <ref> tag; no text was provided for refs named Gemini
  11. ↑ 11.0 11.1 11.2 11.3 Cite error: Invalid <ref> tag; no text was provided for refs named MPEC-2020-D104
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named NEODyS-Eph-Dis
  13. ↑ 13.0 13.1 13.2 Cite error: Invalid <ref> tag; no text was provided for refs named King2020
  14. ↑ 14.0 14.1 14.2 Cite error: Invalid <ref> tag; no text was provided for refs named PseudoMPEC
  15. ↑ 15.0 15.1 15.2 Cite error: Invalid <ref> tag; no text was provided for refs named Howell2020
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named MPC-object
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named NEO-Exchange
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Nomenclature
  19. ↑ 19.0 19.1 Cite error: Invalid <ref> tag; no text was provided for refs named Plait2020
  20. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Baoyin2010
  21. ↑ 21.0 21.1 21.2 21.3 21.4 Cite error: Invalid <ref> tag; no text was provided for refs named Naidu2020
  22. ↑ 22.0 22.1 Cite error: Invalid <ref> tag; no text was provided for refs named Christmas2015
  23. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Horizons2017-2020
  24. ↑ 24.0 24.1 24.2 24.3 24.4 Cite error: Invalid <ref> tag; no text was provided for refs named jpldata
  25. ↑ 25.0 25.1 Cite error: Invalid <ref> tag; no text was provided for refs named Horizons-Hill
  26. ↑ 26.0 26.1 Cite error: Invalid <ref> tag; no text was provided for refs named Gough2020
  27. ↑ 27.0 27.1 27.2 Cite error: Invalid <ref> tag; no text was provided for refs named Boyle2020
  28. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Tancredi1997
  29. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Gohd2019
  30. ↑ 30.0 30.1 30.2 30.3 30.4 Cite error: Invalid <ref> tag; no text was provided for refs named CNEOS
  31. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Horizons2082-CA
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