Sunday, December 11, 2011

Craters Airy and Airy-0 on Mars named after Greenwich astronomer Sir George Biddell Airy

The craters Airy and Airy-0 on Mars were named to commemorate the Greenwich astronomer Sir George Biddell Airy (1801-1892) [1]: Airy-0, a small impact crater with a diameter of 500 meter, is located inside the 40-kilometer-wide Airy crater in the east-west stretching Sinus Meridiani feature just south of the Martian equator.

The center of Airy-0 was chosen to define the Martian prime meridian, the zero point of longitude. On Earth the prime meridian was defined by international agreement in 1881 based on the location of the Royal Observatory in Greenwich near London, England, where Sir Airy was employed as the seventh Astronomer Royal [1,2].
Pinpointing the zero point onto Airy-0 became possible in 1972, when Mariner 9 mapped the surface of Mars at about 1 kilometer resolution [2]:  Merton Davies of the RAND Corporation, who computed an extensive 'control net' of locations, designated Airy-0 as the reference point for the Martian spherical coordinate system. Planet Mars, however, is not exactly a sphere. Like Earth, Mars is flattened at its poles. The overall shape of Mars may be described as a pear, which is further deformed by structures such as the Tharsis Bulge, an uplifted continent about the size of North America [1,3]. 

George Biddell Airy was born at Alnwick in Northumberland on July 27, 1801.  In 1823, he took his B. A. Degree at Trinity College, Cambridge, where he was appointed Plumian Professor of Astronomy at the Cambridge Observatory in 1828. From 1835 until his retirement in 1881 he was Astronomer Royal at the national observatory in Greenwich, where—during his long career and succession of accomplishments in physics, in particular planetary science— he established the prime meridian in the early 1850s [4,5].

Keywords: astronomy, mathematics, geometry, planetary science, areology (science of Mars), areography (geology of Mars), terminology.

References and more to explore
[1] Ulf von Rauchhaupt: Der Neunte Kontinent - Die wissenschaftliche Eroberung des Mars. Fischer Taschenbuch Verlag, Frankfurt am Main, November 2010; pages 104 and 105.
[2] NASA National Aeronautics and Space Administration > Mars Atlas:
[3] The Tharsis Bulge on Mars:
[4] George Biddell Airy: Autobiography of Sir George Biddell Airy (edited by Wilfrid Airy in 1896, produced by Joseph Myers and PG Distributed Proofreaders and released on January 9, 2004) [].
[5] Sir George Biddell Airy K.C.B., M.A., LL.D., D.C.L., F.R.S., F.R.A.S.:

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