Telescopic Martian Dust Storms

BAA Memoirs, Vol. 44

This 168-page A4 book by Richard McKim, Director of the Mars Section, is the first complete narrative account of all the telescopic martian dust storms observed since records began. Many previously unpublished observations by both amateurs and professionals are described and illustrated. The book contains a catalogue, discussion sections, reference maps and charts, and 300 illustrations including a portrait gallery of past and present Mars observers. Abstract The dust storms of Mars have fascinated the planetary observer since the first observed planetwide event of 1909. To an extent predictable, but notoriously variable in amplitude, the dust storms appear as orange, yellow, or yellow–white clouds, best imaged in red light. Today, the majority of telescopic events are still discovered by amateur astronomers. Apart from colour, dust storms exhibit motion and obscure underlying albedo features. Temporary, anomalous darkenings associated with yellow clouds arise from the removal of the thin surface veneer of dusty material to expose darker bedrock. Dust movement also accounts for all long-term albedo changes of the classical martian surface markings. The present work, the result of a wide-ranging survey of the literature since 1659 and much unpublished archival material, identifies dust storms as early as 1704 and as late as the 1990s, but the timecourse of such phenomena has been followed effectively only from the late nineteenth century. The following account draws heavily upon the published and unpublished work of the BAA Mars Section (1892 onwards). The records for 1922–39 and 1943–54 have been analysed for the first time, and the entire archive re-examined. A coordinated narrative account of the dust storms observed during every martian apparition has been produced, so attempting to collate for the first time all the work of the diverse observers and groups. It chronicles the dates, extent and movements of observed yellow clouds (and suspected yellow clouds and obscurations), and provides comprehensive references to the telescopic literature. In the latter respect, the author has tried to cite all relevant telescopic studies conducted since 1901, the limit of Flammarion’s great two-volume work on the planet. Comprehensive narrative accounts of many newly recognised regional storms, and of the encircling storms of 1909, 1924, 1956, 1971, 1973 and 1975 are published here for the first time. A contemporaneous review of the major albedo changes on the planet has identified past dust storm sites, even where the storms themselves were not directly observed. Many new minor events have been detected, whilst in reviewing the extant catalogues, numerous spurious ‘events’ have been shown to be records of limb or polar haze, white cloud, observational errors or duplicate records of the same event.

The account closes with a revised dust storm catalogue, a complete location map, and histograms and statistical analyses of the data. This new study confirms that there are ‘preferred’ emergence sites which vary with time. Hellas features largely in the statistics for the epoch 1909–1988, with the Libya–Isidis emergence site being of major importance up to 1958/59. It is shown that despite the less complete temporal coverage before the 1890s, the eighteenth and nineteenth centuries genuinely appear to have been deficient in major or encircling storms. It will be important to continue the ground-based record for many years in order to improve our statistics of all types of yellow clouds.

Ordering information

Copies can be obtained only from: British Astronomical Association Burlington House Piccadilly London W1J 0DU Tel : 020 7734 4145 Fax : 020 7439 4629 E-mail : office@britastro.org

This Memoir has been published as a book only, and is not available in electronic form ISBN 0-902749-13-7 BAA members resident in the UK or Europe: £10.50, post free Non-members resident in the UK or Europe: £15.00, post free BAA members resident in North America: $22.00 (air-mail) Non-members resident in North America: $32.00 (air-mail) Dollar cheques are accepted; those living elsewhere, please enquire Payment can be made by cheque, or on-line via the Sales page on the BAA website