Английская Википедия:2020 SW

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Шаблон:Use dmy dates Шаблон:Infobox planet

Шаблон:Mp is a tiny near-Earth asteroid discovered by the Mount Lemmon Survey on 18 September 2020, six days before it made its closest approach to Earth. The asteroid passed within Шаблон:Convert from Earth's surface on 24 September 2020 11:13 UT, within the geostationary altitude of Шаблон:Convert. The encounter with Earth perturbed the asteroid's heliocentric trajectory from an Apollo-type orbit to an Aten-type orbit with a semi-major axis within one astronomical unit from the Sun. As a result, the asteroid will not make any close approaches to Earth within Шаблон:Convert in the next 200 years.

With an estimated diameter roughly Шаблон:Convert across, Шаблон:Mp is comparable to the size of a small school bus. Had it impacted Earth, it would mostly have disintegrated as a fireball during atmospheric entry and might have left a common strewn field. Extensive observations of its brightness during the close encounter show that it is an elongated body with a rapid rotation period of 28.5 seconds.

Discovery

Шаблон:Mp was discovered on 18 September 2020 by the Mount Lemmon Survey under astronomer Kacper W. Wierzchoś, stationed at the Mount Lemmon Observatory in Tucson, Arizona. The asteroid was first observed in the constellation Pegasus at an apparent magnitude of 21.4.[1] It was moving at an on-sky rate of 1.41 arcseconds per minute, from a distance of Шаблон:Convert from Earth.[2]

The asteroid was subsequently listed on the Minor Planet Center's Near-Earth Object Confirmation Page (NEOCP) as C378AD2.[3] Follow-up observations were carried out by four other observatories including Pan-STARRS 1 Шаблон:Small and the Catalina Sky Survey Шаблон:Small. Within one day after the asteroid's discovery, the listing was confirmed and publicly announced as Шаблон:Mp on 19 September 2020.[1]

Orbit and classification

Шаблон:Mp is currently on an Earth-crossing Aten-type orbit with an orbital semi-major axis of 0.941 AU and an orbital period of 0.91 years.[4] With a nominal perihelion distance of 0.743 AU and an aphelion distance of 1.140 AU, Шаблон:Mp's orbit extends from Venus to Earth, resulting in occasional close passes with these planets. The nominal minimum orbit intersection distances (MOID) with Venus and Earth are approximately Шаблон:Cvt and Шаблон:Cvt, respectively.[3] Шаблон:Mp has an orbital eccentricity of 0.211 and an inclination of 2.3 degrees to the ecliptic.[4]

Before the Earth encounter on 18 September 2020, Шаблон:Mp had a more distant Apollo-type orbit crossing the path of Earth. It had a perihelion distance of 0.822 AU and a semi-major axis of 1.015 AU, with an orbital period of 1.02 years. The orbit had an orbital eccentricity of 0.190 and an inclination of 4.2 degrees to the ecliptic.[5]

Orbital Elements
Parameter Epoch Period
(p) 		Aphelion
(Q) 		Perihelion
(q) 		Semi-major axis
(a) 		Eccentricity
(e) 		Inclination
(i)
Units (days) AU (°)
Pre-flyby 2020-May-31[5] 373.5 1.208 0.822 1.015 0.1902 4.212°
Post-flyby 2020-Dec-17[4][6] 333.6 1.140 0.743 0.941 0.2112 2.326°

Physical characteristics

Albedo and diameter

Based on an magnitude-to-diameter conversion and a measured absolute magnitude of 29.06, Шаблон:Mp measures between 4 and 9 metres in diameter for an assumed geometric albedo of 0.25 and 0.05, respectively.[4][7] Given its small size, Шаблон:Mp can be compared to a small school bus.[8] It is too small to pose any threat to Earth and its nominal orbit is not known to be on an impact trajectory with the planet. Even had it impacted Earth, it would mostly have disintegrated as a fireball during atmospheric entry and might have left a common strewn field.[8]

Shape and rotation

The Шаблон:Mp close encounter with Earth provided an opportunity for astronomers to take detailed measurements of its light curve to determine the asteroid's rough shape and rotation period. On 24 September 2020, within 10 hours before closest approach to Earth, Шаблон:Mp was continually observed by astronomer Peter Birtwhistle at the Great Shefford Observatory Шаблон:Small for 2 hours and 51 minutes. He derived a period of Шаблон:Val (Шаблон:Val) and a light curve amplitude of 0.73, indicating an elongated shape with a minimum a/b ellipsoid aspect ratio of 1.6. Earlier independent observations of Шаблон:Mp by astronomers at the Northolt Branch Observatories produced similar measurements of the asteroid's light curve, providing a period of Шаблон:Val (Шаблон:Val) and an amplitude of 0.72.[9]

See also

References

Шаблон:Reflist

External links

Шаблон:2020 in space Шаблон:Small Solar System bodies Шаблон:Portal bar Шаблон:Authority control

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  1. ↑ 1,0 1,1 Ошибка цитирования Неверный тег <ref>; для сносок MPEC-2020-S83 не указан текст
  2. ↑ Ошибка цитирования Неверный тег <ref>; для сносок NEODyS-Eph-Dis не указан текст
  3. ↑ 3,0 3,1 Ошибка цитирования Неверный тег <ref>; для сносок PseudoMPEC не указан текст
  4. ↑ 4,0 4,1 4,2 4,3 Ошибка цитирования Неверный тег <ref>; для сносок MPC-object не указан текст
  5. ↑ 5,0 5,1 Ошибка цитирования Неверный тег <ref>; для сносок jpldata не указан текст
  6. ↑ Ошибка цитирования Неверный тег <ref>; для сносок horizons не указан текст
  7. ↑ Ошибка цитирования Неверный тег <ref>; для сносок sizemagnitude не указан текст
  8. ↑ 8,0 8,1 Ошибка цитирования Неверный тег <ref>; для сносок JPL-20200922 не указан текст
  9. ↑ Ошибка цитирования Неверный тег <ref>; для сносок MPB-48-1 не указан текст
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