2005 NB56

2005 NB₅₆, also written as 2005 NB56, is a near-Earth asteroid of the Apollo group.^[2] In 2009, research physicist Edward Drobyshevski and colleagues have suggested that 2005 NB₅₆ could be a possible source of the meteoroid that caused the Tunguska event on 30 June 1908. It has been also suspected to be a dormant comet.^[4]

2005 NB₅₆

Discovery[1]
Discovered by	Mount Lemmon Survey
Discovery site	Summerhaven, Arizona, US
Discovery date	11 July 2005
Designations
MPC designation	2005 NB56
Minor planet category	Apollo NEO
Orbital characteristics[2]
Epoch 14 July 2005 (JD 2453565.5)
Uncertainty parameter 7
Observation arc	17[1] d
Aphelion	2.41707 AU (361.589 Gm)
Perihelion	0.86585 AU (129.529 Gm)
Semi-major axis	1.64146 AU (245.559 Gm)
Eccentricity	0.47251
Orbital period (sidereal)	2.10 yr (768.15 d)
Mean anomaly	25.175°
Mean motion	0° 28m 7.176s /day
Inclination	6.7563°
Longitude of ascending node	112.359°
Argument of perihelion	114.15°
Earth MOID	0.0163799 AU (2,450,400 km)
Jupiter MOID	2.5887 AU (387.26 Gm)
Physical characteristics
Mean diameter	~170 m[3]
Absolute magnitude (H)	22.9[2]

Possible source of the Tunguska event bolide

One study "suggests that a chunk of a comet caused the 5-10 megaton fireball, bouncing off the atmosphere and back into orbit around the sun."^[4]

This object made a close approach to Earth when it was discovered in 2005 and will do so again in 2045.^[5] This object has a poorly known orbit and was only observed over an observation arc of 17 days, not sufficient to predict its position in 1908 with sufficient accuracy.^[2]