is an asteroid, classified as a near-Earth object and a potentially hazardous asteroid of the Apollo group. It is a possible candidate for the parent body of the Chelyabinsk superbolide.
Discovery, orbit and physical properties was discovered by Richard A. Kowalski on 10 March 2011 while observing for the Mount Lemmon Survey.Discovery MPEC
Its orbit is typical of Apollo asteroids and is characterized by significant eccentricity (0.54), low inclination (3.36º), and a semi-major axis of 1.65 AU.MPC data on 2011 EO40 Upon discovery, it was classified as an Earth crosser, a near-Earth asteroid (NEA) and a potentially hazardous asteroid (PHA) by the Minor Planet Center. It was listed on the Sentry Risk Table for less than one day. Its orbit is in need of additional observations to determine if it is part of an asteroid family; as of October 2015 the orbit is determined using just twenty observations spanning an observation arc of 34 days. has an absolute magnitude of 21.5, which gives a characteristic diameter of about .
Relationship to the Chelyabinsk superbolide Recent calculations indicate that this object is a plausible candidate to be the parent body of the Chelyabinsk superbolide, since its orbit is very similar to the computed, pre-impact path of the Chelyabinsk meteoroid. It has relatively frequent close encounters with Venus, the Earth–Moon system, and Mars. It had a close encounter with Earth on 28 January 2011 at , and it will have a nominal Earth approach on 23 September 2025 at about . Asteroid experiences close approaches to the Earth–Moon system following a rather regular pattern, every 17 years approximately due to the combined action of multiple secular resonances.
Visibility had opposition windows on 7 June 2016 at magnitude 24.5, and 28 May 2018 at magnitude 24.6 but was not observed during either opposition. The asteroid was recovered on 15 August 2025 by Pan-STARRS. The best observation window was on 2–23 September 2025. Depending on the Earth approach distance (0.04–0.12 AU), it should have been brighter than magnitude 19.
See also Carbonaceous chondrite Meteorite
Notes
This is assuming an albedo of 0.20–0.04.
References (2.7e-07 = 1 in 3,704,000 chance)
External links data at MPC MPEC 2011-E59 : 2011 EO40 (Discovery MPEC) Russian meteor may have gangmates in tow, Nature, short article Has the Chelyabinsk Meteor Parent Asteroid Been Found?, Bad Astronomy blog entry