101955 Bennu

101955 Bennu
Mosaic image of 101955 Bennu consisting of 12 PolyCam images collected on 2 December 2018 by OSIRIS-REx from a range of 24 km (15 mi).
Discovered byLINEAR
Discovery siteLincoln Lab's ETS
Discovery date11 September 1999
MPC designation(101955) Bennu
Named after
1999 RQ36
Apollo · NEO · PHA
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc13.36 yr (4880 days)
Aphelion1.3559 au (202.84 Gm)
Perihelion0.89689 au (134.173 Gm)
1.1264 au (168.51 Gm)
1.20 yr (436.65 d)
28,000 metres per second (63,000 mph)
0° 49m 28.056s / day
Earth MOID0.0032228 au (482,120 km)
Venus MOID0.194 au (29,000,000 km)[1]
Mars MOID0.168 au (25,100,000 km)[1]
Jupiter MOID3.877 au (580.0 Gm)
Proper orbital elements[3]
301.1345 deg / yr
1.19548 yr
(436.649 d)
Physical characteristics
Mean radius
245.03±0.08 m[4]
Equatorial radius
(282.37±0.06) × (268.05±0.06) m[4]
Polar radius
249.25±0.06 m[4]
0.782±0.004 km2[4]
Volume0.0615±0.0001 km3[4]
Mass7.329±0.009×1010 kg[4]
Mean density
1.190±0.013 g/cm3[4]
Equatorial surface gravity
6 micro-g[5]
4.296057 h (0.1790024 d)[4]
North pole right ascension
North pole declination
Surface temp.minmeanmax

101955 Bennu (provisional designation 1999 RQ36)[8] is a carbonaceous asteroid in the Apollo group discovered by the LINEAR Project on 11 September 1999. It is a potentially hazardous object that is listed on the Sentry Risk Table with the second-highest cumulative rating on the Palermo Technical Impact Hazard Scale.[9] It has a cumulative 1-in-2,700 chance of impacting Earth between 2175 and 2199.[10][11] It is named after the Bennu, the ancient Egyptian mythological bird associated with the Sun, creation, and rebirth.

101955 Bennu has a mean diameter of approximately 492 m (1,614 ft; 0.306 mi) and has been observed extensively with the Arecibo Observatory planetary radar and the Goldstone Deep Space Network.[12][13][14]

Bennu is the target of the OSIRIS-REx mission which is intended to return samples to Earth in 2023 for further study.[15][16][17] On 3 December 2018, the OSIRIS-REx spacecraft arrived at Bennu after a two-year journey.[18] Before attempting to obtain a sample from the asteroid, it will map out Bennu's surface in detail and orbit the asteroid to calculate its mass.[19] On 18 June 2019, NASA announced that OSIRIS-REx managed to get even closer and capture an image at a distance of 0.4 miles (0.64 km) from Bennu's surface.[20]

Discovery and observation

Series of Goldstone radar images showing Bennu's rotation.

Bennu was discovered on 11 September 1999 during a Near-Earth asteroid survey by the Lincoln Near-Earth Asteroid Research (LINEAR).[1] The asteroid was designated 1999 RQ36 and classified a near-Earth asteroid. Bennu approached close to Earth and it was observed extensively by the Arecibo Observatory and the Goldstone Deep Space Network using radar imaging as Bennu closely approached Earth on 23 September 1999.[12][13]


The name Bennu was selected from more than eight thousand student entries from dozens of countries around the world who entered a "Name That Asteroid!" contest run by the University of Arizona, The Planetary Society, and the LINEAR Project in 2012.[2][8] Third-grade student Michael Puzio from North Carolina proposed the name in reference to the Egyptian mythological bird Bennu. To Puzio, the OSIRIS-REx spacecraft with its extended TAGSAM arm resembled the Egyptian deity, which is typically depicted as a heron.[2]

Its features will be named after birds and bird-like creatures in mythology.[21]

Other Languages
Afrikaans: 101955 Bennu
العربية: بينو 101955
čeština: Bennu (planetka)
Ελληνικά: 101955 Μπεννού
español: (101955) Bennu
Esperanto: 101955 Bennu
français: (101955) Bénou
한국어: 101955 베누
Արեւմտահայերէն: 101955 Պէնու
Bahasa Indonesia: 101955 Bennu
italiano: 101955 Bennu
Latina: 101955 Bennu
Lëtzebuergesch: (101955) Bennu
magyar: 101955 Bennu
Minangkabau: 101955 Bennu
português: 101955 Bennu
română: 101955 Bennu
русский: (101955) Бенну
svenska: 101955 Bennu
தமிழ்: 101955 பென்னு
Türkçe: 101955 Bennu
українська: 101955 Бенну
Tiếng Việt: 101955 Bennu