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    • Closest Approaches to the Earth by Comets

    The following table lists, in order of increasing geocentric distance, the closest known approaches to the earth by comets. In order to qualify for this listing, the approach must have occurred during an observed apparition, although in some cases the object was not under observation at the time of closest approach.

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    A list of closest approaches to the earth by minor planets is also available.

    The dates of closest approach are given in Terrestrial Time (TT), although at the precision of this table they can be considered to be in Universal Time (UT). For comparison, the mean distance of the moon is 0.0026 AU = 384400 km = 238900 miles. (1 AU is approximately the mean distance of the earth from the sun = 149597870 km = 92955810 miles.) 

    Distance  Date (TT)       Permanent designation
  (AU)

 0.0151   1770 July  1.7      D/1770 L1 (Lexell)
 0.0229   1366 Oct. 26.4    55P/1366 U1 (Tempel-Tuttle)
 0.0237   2016 Mar. 22.65     P/2016 BA14 (PANSTARRS)
 0.0312   1983 May  11.5      C/1983 H1 (IRAS-Araki-Alcock)
 0.0334    837 Apr. 10.5     1P/837 F1 (Halley)
 0.0358   2016 Mar. 21.52  252P/LINEAR
 0.0366   1805 Dec.  9.9     3D/1805 V1 (Biela)
 0.0390   1743 Feb.  8.9      C/1743 C1
 0.0394   1927 June 26.8     7P/Pons-Winnecke
 0.0437   1702 Apr. 20.2      C/1702 H1
 0.0555   2014 May  29.33  209P/LINEAR
 0.0601   2011 Aug. 15.34   45P/Honda-Mrkos-Pajdusakova
 0.0617   1930 May  31.7    73P/1930 J1 (Schwassmann-Wachmann)
 0.0628   1983 June 12.8      C/1983 J1 (Sugano-Saigusa-Fujikawa)
 0.0682   1760 Jan.  8.2      C/1760 A1 (Great comet)
 0.0787   2006 May  12.4    73P/Schwassmann-Wachmann
 0.0839   1853 Apr. 29.1      C/1853 G1 (Schweizer)
 0.0879   1797 Aug. 16.5      C/1797 P1 (Bouvard-Herschel)
 0.0884    374 Apr.  1.9     1P/374 E1 (Halley)
 0.0898    607 Apr. 19.2     1P/607 H1 (Halley)
 0.0934   1763 Sept.23.7      C/1763 S1 (Messier)
 0.0964   1864 Aug.  8.4      C/1864 N1 (Tempel)
 0.0982   1862 July  4.6      C/1862 N1 (Schmidt)
    Note: This list is intended to be complete for comets discovered after 1700 that approached the earth to within 0.1020 AU. It also includes a number of well-documented earlier approaches by periodic comets. C/1491 B1 allegedly came to within 0.0094 AU on 1491 Feb. 20.0 TT, but the orbit of this comet is very uncertain. Additional (uncertain) ancient approaches are given in `Close Encounters and Collisions of Comets with the Earth' by Z. Sekanina and D. K. Yeomans (Astron. J. 89, 154-161).