Letter | Published:

The trajectory, structure and origin of the Chelyabinsk asteroidal impactor

Nature volume 503, pages 235237 (14 November 2013) | Download Citation


Earth is continuously colliding with fragments of asteroids and comets of various sizes. The largest encounter in historical times occurred over the Tunguska river in Siberia in 1908, producing1,2 an airburst of energy equivalent to 5–15 megatons of trinitrotoluene (1 kiloton of trinitrotoluene represents an energy of 4.185 × 1012 joules). Until recently, the next most energetic airburst events occurred over Indonesia3 in 2009 and near the Marshall Islands4 in 1994, both with energies of several tens of kilotons. Here we report an analysis of selected video records of the Chelyabinsk superbolide5 of 15 February 2013, with energy equivalent to 500 kilotons of trinitrotoluene, and details of its atmospheric passage. We found that its orbit was similar to the orbit of the two-kilometre-diameter asteroid 86039 (1999 NC43), to a degree of statistical significance sufficient to suggest that the two were once part of the same object. The bulk strength—the ability to resist breakage—of the Chelyabinsk asteroid, of about one megapascal, was similar to that of smaller meteoroids6 and corresponds to a heavily fractured single stone. The asteroid broke into small pieces between the altitudes of 45 and 30 kilometres, preventing more-serious damage on the ground. The total mass of surviving fragments larger than 100 grams was lower than expected7.

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We thank D. Částek and O. Popova and her team (V. Emelyanenko, A. Kartashova, D. Glazachev and E. Biryukov) for providing the nocturnal in situ calibration images. We are obliged to all the videographers who posted videos of the Chelyabinsk superbolide on the internet. The work of J.B., P.S. and L.S. was supported by grant no. P209/11/1382 from GAČR and Praemium Academiae. The Czech institutional project was RVO:67985815. The work of P.B., P.W. and D.C. was supported in part by the Natural Sciences and Engineering Research Council of Canada and NASA’s Meteoroid Environment Office.

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  1. Astronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondřejov, Czech Republic

    • Jiří Borovička
    • , Pavel Spurný
    •  & Lukáš Shrbený
  2. Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7, Canada

    • Peter Brown
    • , Paul Wiegert
    •  & David Clark
  3. Centre for Planetary Science and Exploration, University of Western Ontario, London, Ontario N6A 5B7, Canada

    • Peter Brown
    • , Paul Wiegert
    •  & David Clark
  4. Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V Holešovičkách 41, CZ-18209 Praha 8, Czech Republic

    • Pavel Kalenda


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J.B. made measurements from most of the videos, computed the bolide trajectory and velocity, and analysed its atmospheric fragmentation and dust trail. P.S. organized the calibrations, made measurements from the calibration images and participated in interpreting the results. P.B. participated in the acoustic analysis and in interpreting the results. P.W. and D.C. performed the orbital integration, analysed the parent-body linkage and analysed the asteroid visibility before impact. P.K. found many important videos and participated in the acoustic analysis. L.S. prepared the calibrations and participated in video measurements. All authors commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Jiří Borovička.

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