Messier A

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Messier A

(current IAU-approved name; formerly W. Pickering and before that W.H. Pickering)

Lat: 2.02°S, Long: 46.95°E, Diam: 10.73 km, Depth: 2.24 km, Rükl 48, Copernican

external image normal_Messier-A_LO-IV-060H_LTVT.JPG
LO-IV-060H (Matching LO view of Messier) The namesake crater Messier lies just out of this field to the right (east).


LPOD Photo Gallery Lunar Orbiter Images Apollo Images ASU Apollo Image Archive

  • Frame 5041, made by Lunar Orbiter 5, shows a westward oblique view of both Messier and Messier A. Note the bright retro-reflection ("Heiligenschein") near the horizon.
  • AS10-35-5205, made through one of the small windows of Apollo 10's CM Charlie Brown, shows the Messier'-twins and one of LM Snoopys four nozzle clusters (bottom right corner).
  • AS11-44-6616 is one of Apollo 11's un-labeled orbital Hasselblad photographs which show both craters Messier and Messier A near the frame's lower right corner.
  • AS16-122-19535 is one of seven photographs which show the rotation of the Ascent Stage of Apollo 16's LM Orion during Stations-Keeping (before docking). Note the Messier twins at right!
  • Apollo 15's orbital panoramic stereo frames AS15-P-10124 and 10129 also show Messier A.
  • Research Lunar Orbiter and Apollo photographs: Danny Caes


(LAC zone 79B2) LAC map Geologic map AIC map LTO map


Description: Wikipedia


Additional Information


  • The present IAU name (Messier A) is derived from that of the nearby crater (Messier).
  • According to Mary Blagg's Collated List of 1913, this crater (catalog entry 4255) was known to Beer and Mädler, and to Neison, as Messier A. Schmidt called it Messier East (see the note on IAU directions) or, occasionally, Messier A.
  • In the 1928 IAU Transactions it is reported that the Lunar Commission considered adopting Krieger's suggestion of naming Hipparchus G (Catalog Number 3609, near Catalog Number 3607 for which Krieger suggested E. Pickering) W. Pickering after Prof. William H. Pickering (1858-1938), but that Prof. Pickering objected, saying that if a crater was to be named after him, he preferred it to be one "in which he is personally interested and on which he had worked."
  • Following his wish, in the original IAU nomenclature of Blagg and Müller (1935) the name for the present catalog entry was changed to W. H. Pickering, honoring a living American astronomer and member of the Lunar Nomenclature Commission.
  • In Table III of the first volume of the LPL's Photographic Lunar Atlas (approved by the IAU in 1961), Gerard Kuiper recommeded deleting the "H." changing the official name to W. Pickering.
  • By the time they got to the Rectified Lunar Atlas (approved by the IAU in 1964), the LPL, for reasons explained in a news report about that IAU meeting, recommended reverting the name to Messier A with W. H. Pickering's commemoration being combined with that of E. C. Pickering in the unrelated crater formerly known as E. Pickering.
  • Since the deletion of W. Pickering in 1964, Messier A has been the official IAU name for this crater.

LPOD Articles

A Comet and a Butterfly
A Tunnel Thru the Moon
Fertility Central
Butterfly Wings & Railway Tracks

APOD Articles

Messier craters in Stereo (Red-Cyanblue anaglyph of orbital Apollo 11 photograph, by Patrick Vantuyne).


  • Wood, C.A. Messier on the Moon. S&T Online article.
  • Hill, Harold. A Portfolio of Lunar Drawings, pages 22, 23 (the evening terminator from Messier A to Taruntius), and pages 210-214 (the Messier twins).
  • About W.H.Pickering himself (and his observations of the moon): EPIC MOON; a History of Lunar Exploration in the age of the Telescope (W.P.Sheehan/ T.A.Dobbins).

W. H. Pickering in the Sourcebook Project (William R. Corliss)

- In: Mysterious Universe, a handbook of astronomical anomalies (1979) :
  • The Lunar Vegetation (Journal of the British Astronomical Association, 1926)
  • Stationary Radiants (Journal of the British Astronomical Association, 1915)
  • Curious Geometrical Figures appearing upon Mars (Scientific American, 1926)