This report was published in the BAA Journal for 2006 February

Mars was at perihelic opposition on 2005 November 7, and a huge number of observations – as yet too many even to count – have been received from 95 persons. These data date from as long ago as 2004 November, and daily coverage has been achieved for many consecutive months. The seasonal retreat of the S. polar cap has been well followed, and the diurnal and orographic clouds have lately been attracting interest. The closeness of the approach enabled many superb images, videos and drawings to be made. Damian Peach’s image on the front cover is a splendid example of his work. In this short note we focus purely upon the exciting recent dust storm activity. Smaller scale activity was observed earlier in the apparition, but in October there was a regional-scale event.

      A dust storm alert appeared in BAA E-Circular No. 204, dated 2005 October 21, and BAA Circular No. 800 also carried this news. Although few UK observers could witness the event, it was well seen from the USA, and an excellent series of images by Clay Sherrod appears on the front cover of the February 2006 issue of the Journal. By October 21, fingers of dust had spread into (or more likely, secondary dust cores had freshly arisen over) N. Argyre and southern Solis Lacus. The Argyre activity rapidly spread southeast into S. Noachis and began to impinge upon the S. polar cap. On October 28 a spectacular resurgence of activity occurred over Margaritifer Sinus–Aram (Thymiamata), as the original core of the storm was decaying. This latter activity (captured in detail by the HST) expanded to the SE, and Meridiani Sinus was greatly obscured by October 30. The small summer SPC was affected by the dust, becoming faint and hard to see.

      The international nature of our Mars patrol enabled the daily timecourse of the storm to be followed in detail. The dust reached and dimmed Hellespontus to the east, but no dust core arose in neighbouring Hellas, nor did the event penetrate beyond Solis Lacus to the west. The event did not last more than a few weeks, but a persistent dusty haze veiled some of the markings – especially around Noachis–Argyre–Margaritifer Sinus – for some time afterward.

      There will be a huge amount of material available for later analysis, and I hope our members will help to keep a full daily record going for several months yet.
 

Richard McKim, Director