The Chelyabinsk meteor (Russian: Челябинский метеорит, romanised: Chelyabinskiy meteorit) was a superbolide that entered Earth's atmosphere over the southern Ural region in Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC).

It was caused by an approximately 18-metre-diameter (60 ft), 9,100-tonne (10,000-short-ton) near-Earth asteroid that entered the atmosphere at a shallow 18‐degree angle with a speed relative to Earth of 19 kilometres per second (69,000 km/h; 43,000 mph).

[6] The explosion generated a bright flash, producing a hot cloud of dust and gas that penetrated to 26 km (86,000 ft), and many surviving small fragmentary meteorites.

The asteroid had a total kinetic energy before atmospheric impact equivalent to the blast yield of 400–500 kilotonnes of TNT (1.7–2.1 petajoules), estimated from infrasound and seismic measurements.

All of the injuries were due to indirect effects rather than the meteor itself, mainly from broken glass from windows that were blown in when the shock wave arrived, minutes after the superbolide's flash.

It is the largest known natural object to have entered Earth's atmosphere since the 1908 Tunguska event, which destroyed a wide, remote, forested, and very sparsely populated area of Siberia.

The earlier-predicted and well-publicized close approach of a larger asteroid on the same day, the roughly 30 m (100 ft) 367943 Duende, occurred about 16 hours later; the very different orbits of the two objects showed they were unrelated to each other.

Local residents witnessed extremely bright burning objects in the sky in Chelyabinsk, Kurgan, Sverdlovsk, Tyumen, and Orenburg Oblasts, the Republic of Bashkortostan, and in neighbouring regions in Kazakhstan,[8][9][10] when the asteroid entered the Earth's atmosphere over Russia.

[20] Witnesses in Chelyabinsk said that the air of the city smelled like "gunpowder", "sulfur" and "burning odors" starting about 1 hour after the fireball and lasting all day.

The last time a similar phenomenon was observed in the Chelyabinsk region was the Kunashak meteor shower of 1949, after which scientists recovered about 20 meteorites weighing more than 200 kg (440 lb) in total.

[27] Preliminary estimates released by the Russian Federal Space Agency indicated the object was an asteroid moving at about 30 km/s (110,000 km/h; 67,000 mph) in a "low trajectory" when it entered Earth's atmosphere.

[29] Early analysis of CCTV and dashcam video posted online indicated that the meteor approached from the southeast, and exploded about 40 km (25 mi) south of central Chelyabinsk above Korkino at a height of 23.3 kilometres (76,000 ft), with fragments continuing in the direction of Lake Chebarkul.

[1][30][31][32] On 1 March 2013, NASA published a detailed synopsis of the event, stating that at peak brightness (at 09:20:33 local time), the meteor was 23.3 km (76,000 ft) high, located at 54.8°N, 61.1°E.

[49] Additional scientific analysis of US military infrasound data was aided by an agreement reached with US authorities to allow its use by civilian scientists, implemented only about a month before the Chelyabinsk meteor event.

[15][49] A preliminary estimate of the explosive energy by astronomer Boris Shustov, director of the Russian Academy of Sciences Institute of Astronomy, was 200 kilotonnes of TNT (840 TJ),[50] another using empirical period-yield scaling relations and the infrasound records, by Peter Brown of the University of Western Ontario gave a value of 460–470 kilotonnes of TNT (1,900–2,000 TJ) and represents a best estimate for the yield of this airburst; there remains a potential "uncertainty [in the order of] a factor of two in this yield value".

[51][52] Brown and his colleagues also went on to publish a paper in November 2013 which stated that the "widely referenced technique of estimating airburst damage does not reproduce the [Chelyabinsk] observations, and that the mathematical relations found in the book The Effects of Nuclear Weapons which are based on the effects of nuclear weapons – [which is] almost always used with this technique – overestimate blast damage [when applied to meteor airbursts]".

[61] The intense light from the meteor, momentarily brighter than the Sun, also produced injuries, resulting in more than 180 cases of eye pain, and 70 people subsequently reported temporary flash blindness.

Despite not knowing the origin of the intense flash of light, Karbysheva thought it prudent to take precautionary measures by ordering her students to stay away from the room's windows and to perform a duck and cover manoeuvre and then to leave the building.

Karbysheva, who remained standing, was seriously lacerated when the blast arrived and window glass severed a tendon in one of her arms and left thigh; none of her students, whom she ordered to hide under their desks, suffered cuts.

Colonel General Nikolay Bogdanov, commander of the Central Military District, created task forces that were directed to the probable impact areas to search for fragments of the asteroid and to monitor the situation.

[79] On the day of the impact, Bloomberg News reported that the United Nations Office for Outer Space Affairs had suggested the investigation of creating an "Action Team on Near-Earth Objects", a proposed global asteroid warning network system, due to 2012 DA14's approach.

[86] There have been incidents in the previous century involving a comparable energy yield or higher: the 1908 Tunguska event, and, in 1963, off the coast of the Prince Edward Islands in the Indian Ocean.

[89] Based on its entry direction and speed of 19 kilometres per second (68,000 km/h; 43,000 mph), the Chelyabinsk meteor apparently originated in the asteroid belt between Mars and Jupiter.

The metamorphism in the chondrules in the meteorite samples indicates the rock comprising the meteor had a history of collisions and was once several kilometres below the surface of a much larger LL chondrite asteroid.

[90] In the aftermath of the air burst of the body, many small meteorites fell on areas west of Chelyabinsk, generally at terminal velocity, about the speed of a piece of gravel dropped from a skyscraper.

From the measured time difference between the shadow generating meteor to the moment of impact, scientists calculated that this meteorite hit the ice at about 225 m/s (740 ft/s), 64 per cent of the speed of sound.

[102] New York City planetarium director Neil deGrasse Tyson stated the Chelyabinsk meteor was unpredicted because no attempt had been made to find and catalogue every 15 m (49 ft) near-Earth object.

[105][106] Several groups independently derived similar orbits for the object, but with sufficient variance to point to different potential parent bodies of this meteoroid.

[112] Preliminary calculations rapidly showed that the object was unrelated to the long-predicted close approach of the asteroid 367943 Duende, that flew by Earth 16 hours later at a distance of 27,700 km (17,200 mi).

[11][117][118] The Sodankylä Geophysical Observatory,[29] Russian sources,[119] the European Space Agency,[120] NASA[11] and the Royal Astronomical Society[121] all concluded that the two asteroids had widely different trajectories and therefore could not have been related.