101955 Bennu

101955 Bennu

Mosaic image of Bennu consisting of 12 PolyCam images collected on 2 December 2018 by OSIRIS-REx from a range of 24 km (15 mi).
Discovery[1]
Discovered by	LINEAR
Discovery site	Lincoln Lab's ETS
Discovery date	11 September 1999
Designations
MPC designation	(101955) Bennu
Pronunciation	/bɛˈnuː/
Named after	Bennu
Alternative designations	1999 RQ36
Minor planet category	Apollo · NEO · PHA
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	13.36 yr (4880 days)
Aphelion	1.3559 au (202.84 Gm)
Perihelion	0.89689 au (134.173 Gm)
Semi-major axis	1.1264 au (168.51 Gm)
Eccentricity	0.20375
Orbital period	1.20 yr (436.65 d)
Average orbital speed	28.0 km/s (63,000 mph)
Mean anomaly	101.7039°
Mean motion	0° 49^m 28.056^s / day
Inclination	6.0349°
Longitude of ascending node	2.0609°
Argument of perihelion	66.2231°
Earth MOID	0.0032228 au (482,120 km)
Venus MOID	0.194 au (29,000,000 km)[2]
Mars MOID	0.168 au (25,100,000 km)[2]
Jupiter MOID	3.877 au (580.0 Gm)
TJupiter	5.525
Proper orbital elements[3]
Proper eccentricity	0.21145
Proper inclination	5.0415°
Proper mean motion	301.1345 deg / yr
Proper orbital period	1.19548 yr (436.649 d)
Physical characteristics[6]
Dimensions	282.37 × 268.05 × 249.25 ± 0.06 m
Mean radius	245.03±0.08 m
Equatorial radius	282.37±0.06 m
Polar radius	249.25±0.06 m
Surface area	0.782±0.004 km^2
Volume	0.0615±0.0001 km^3
Mass	(7.329±0.009)×10^10 kg
Mean density	1.190±0.013 g/cm^3
Equatorial surface gravity	6 micro-g[4]
Rotation period	4.296057±0.000002 h
Axial tilt	177.6±0.11°
North pole right ascension	+85.65±0.12°
North pole declination	−60.17±0.09°
Geometric albedo	0.044±0.002
Surface temp. min mean max Kelvin[5] 236 259 279 Fahrenheit -34.6 6.8 42.8 Celsius -37 -14 6
Spectral type	B[1][6] F[7]
Absolute magnitude (H)	20.9

101955 Bennu (provisional designation 1999 RQ₃₆) is a carbonaceous asteroid in the Apollo group discovered by the LINEAR Project on 11 September 1999.

Bennu has a 1 in 2,700 chance of hitting Earth between the year 2175 and 2199.

It is named after the Bennu, the ancient Egyptian mythological bird associated with the Sun, creation, and rebirth.

Bennu has an average diameter of 492 metres (1,614 feet).

Bennu was the target of the OSIRIS-REx mission which returned samples to Earth in 2023 for further study.

Bennu is the second-highest on the cumulative rating on the Palermo technical impact hazard scale.

It is believed that Bennu broke off from another asteroid in the asteroid belt, but the gravitational pull of Saturn dislodged it into the range of Earth.

Bennu orbits the Sun every 1.2 years. It comes within 0.002 astronomical units of the earth every 6 years.

Some believe that if Bennu enters a specific hole between the earth and the moon its orbit could change in a way that would make it likely to hit Earth.

References

1. "JPL Small-Body Database Browser: 101955 Bennu (1999 RQ36)" (2017-09-01 last observation. Solution includes non-gravitational parameters). Jet Propulsion Laboratory. Archived from the original on 19 March 2018. Retrieved 20 August 2016.
2. "(101955) Bennu = 1999 RQ36 Orbit". Minor Planet Center. Retrieved 2018-03-21.
3. "(101955) Bennu". NEODyS. University of Pisa. Retrieved 1 December 2015.
4. Barnouin, O. S. (March 19, 2019). "Shape of (101955) Bennu indicative of a rubble pile with internal stiffness". Nature Geoscience. 12 (4): 247–252. Bibcode:2019NatGe..12..247B. doi:10.1038/s41561-019-0330-x. PMC 6505705. PMID 31080497.
5. "Planetary Habitability Calculators". Planetary Habitability Laboratory. University of Puerto Rico at Arecibo. Archived from the original on 5 September 2019. Retrieved 6 December 2015.
6. Lauretta, D. S. (March 19, 2019). "The unexpected surface of asteroid (101955) Bennu". Nature. 568 (7750): 55–60. Bibcode:2019Natur.568...55L. doi:10.1038/s41586-019-1033-6. PMC 6557581. PMID 30890786.
7. Hergenrother, Carl W; Maria Antonietta Barucci; Barnouin, Olivier; Bierhaus, Beau; Binzel, Richard P; Bottke, William F; Chesley, Steve; Clark, Ben C; Clark, Beth E; Cloutis, Ed; Christian Drouet d'Aubigny; Delbo, Marco; Emery, Josh; Gaskell, Bob; Howell, Ellen; Keller, Lindsay; Kelley, Michael; Marshall, John; Michel, Patrick; Nolan, Michael; Rizk, Bashar; Scheeres, Dan; Takir, Driss; Vokrouhlický, David D; Beshore, Ed; Lauretta, Dante S (2018). "Unusual polarimetric properties of (101955) Bennu: similarities with F-class asteroids and cometary bodies". Monthly Notices of the Royal Astronomical Society: Letters. 481 (1): L49–L53. arXiv:1808.07812. Bibcode:2018MNRAS.481L..49C. doi:10.1093/mnrasl/sly156.