Further references: ARRAKIS, ATMOSPHERE OF BEKJRE THE ATREIDES; Pardot Kynes, Ecology of Dune, tr. Ewan Gwatan, Arrakis Studies 24 {Grumman. United Worlds), Harq al-Ada, The Story ofliel-Kynes (Work-in-Progress, Arabs Studies, Temp. Ser. 109, Lib. Conf.) ARRAKIS, Geology. (A multitude of papers have appeared during the last several thousand years discussing the origin, evolution, and present state of planets and planetary systems. The geologic history of Arrakis is fascinating, but no more so than of a great number of other planets. No good or recent ARRAKIS GEOLOGY 33 ARRAKIS GEOLOGY review of its geology exists The information presented here is cuBed from many published reports, too numerous to list The only references given are to those papers which contain information of special interest) GEOMETRIC ASPECTS Arrakis revolves about Canopus at a mean distance of 87 million kilometers, significantly closer than most C subclass planets, C designating third major from the primary TT" planet's orbtt about Canopus was roughly circular about 5,000 years ago However, the second (B) and fourth (D) planets circling Canopus, neither habitable, are much larger than Arrakis The inner, Menans, has a mean equatorial radius of 7,862 kilometers while the outer, Extans, has a radius of 8,112 kilometers Arrakis by com parjson has & conespontim radius of only 6,128 kilometers (actually 6127 9621438 talome ters as of year 14521 tot those readers inter- ested in such details) Menans and Extans also have highly elliptical orbits lying well outside the ecliptic plane defined by the orbit of Arrakis about Canopus As a result of the gravitational pulls of these planets informally called the Twins, Arrakis ih now known to achieve a highly eccentric orbit maxi mum elhpttcity 2 1, every 12,323 years The Twins also have a profound impact upon Anakeen geology and tectonics The length of the year vanes from 295 standard days to 595 At present it is 353 days When Arrakis is in its most elliptical phaseseasonal changes are extreme Winters are extremely severe all over the planet Throughout historical times the orbit has been roughly circular for the most part widi very little in the way of seasonal change Only the geological record and theoretical calculations tell us that conditions dunng the ARRAKJS, GEOLOGY ARRAKIS, GEOLOGY past were drastically different from those we now experience. Arrakis has two natural moons. A third was destroyed by impact from an on-rushing asteroid/comet. A ring structure was formed, circling the planet, but most of the debris impacted the planet's surface. Since the moon lay in Arrakis's ecliptic plane, die ring of dust caused a major reduction in star energy striking the surface. Hence surface temperatures were reduced and aft ice age occurred. Many life species perished while others assumed dominance.