The opposition of Mars, 2010: Part I

2018 May 19

Richard McKim

Introduction
Second in the present series of aphelic encounters, the planet was undergoing mid-northern spring at its closest approach. Opposition occurred on 2010 Jan 29 at Ls= 44°, when Mars lay in Cancer with a favourable declination of +22°, with the latitude of the sub-Earth point (or of the centre of the disk, De) equal to +14.7°. The planet was closest on Jan 27, at a maximum disk diameter (D) of only 14.1 arcsec. D remained above 6″ from 2009 Sep 9 till 2010 Jun 1. Key seasonal dates are given in Table 1.

The value of De varied from -25° in 2009 Mar to 0.0° on Aug 15, then increased northwards to a maximum of +18.8° in early Dec, falling to +12.1° by 2010 late Feb, and rising to +26° in July.

Compared with 2007-’08, the winter of 2009-’10 was bitterly cold throughout Northern Europe and America, frequently bringing heavy snowfall and very low temperatures, particularly around Mars’ opposition. The Director often had to trudge through deep snow to reach his observatory in 2010 Jan-Feb. Nevertheless, with 149 contributing observers (Table 2) there were few gaps in our coverage, and detailed analysis of the results has again proved to be very time-consuming.

The first records comprised images for 2009 March 23 (Ls= 232°, D= 4.2″) by Tomio Akutsu, and the final record was a disk drawing by Gianluigi Adamoli dated 2010 Sep 29 (Ls= 156°, D= 4.2″), covering 79% of a martian year. There were 8,258 observations: 7,474 images and 784 drawings. Days per month logged (actual/possible) were: 2009 Mar 5/31, Apr 7/30, May 9/31, Jun 9/30, Jul 13/31, Aug 28/31, Sep 29/30, Oct 30/31, Nov 30/30, Dec 31/31, 2010 Jan 31/31, Feb 28/28, Mar 31/31, Apr 30/30, May 31/31, Jun 28/30, Jul 16/31, Aug 10/31, Sep 3/30.

The state of contemporary image-processing at this epoch was usefully reviewed by Sean Walker.1 Long series of images were provided by Akutsu, Maxson, Morita, Peach, Poupeau, Tasselli and Yunoki. Abel, Adachi, Adamoli, Bailey, Biver, Grego, Macsymowicz, Smet and the Director each contributed 30 or more drawings, and of the latter group Adamoli, Bailey, Biver and the Director also took digital images… (continued)

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