It later became the Imperium's center under Muad'Dib's empire. It was the original and for a long time sole source of the Spice Melange, which was vitally important for space travel. Eventually, because of the vision of Pardot Kynes it was terraformed into a green world.
Arrakis has a density of 4.95 g/cm3 and an acceleration due to gravity of 864 cm/sec2. With such a gravitational attraction, the light gases such as hydrogen and helium have all but escaped into space.
Atmospheric pressure at the equator is 760 mm, about average for a planet of this diameter and mass.
Along with the local star group, there is an extensive dust cloud that permeates the Canopus near-space. This dust cloud was first detected by the Arrakian astronomer Chelin in 12704 AG. Evidence In 12984 AG correlated ice-age-like periods with the dust cloud opacity: the peculiar velocity of Canopus carried the cloud along with the planetary system through regions of varying cloud opacity. This had the resulting effect of reducing the radiation incidents on Arrakis, thus triggering near ice-age conditions. A similar, but even more severe shift in conditions occurred when Arrakis's third moon was destroyed by an asteroid/comet some 200,000 years ago.
Arrakis revolves about Canopus at a mean distance of 87 million kilometers (significantly closer than most C subclass planets). Planetary rotation is in the B class, meaning that the general air circulation was broken up into eddies (cyclones and anticyclones). The planet's orbit was roughly circular (and the axis of rotation was directed almost perpendicular to its ecliptic plane; Because of this there was no observable seasons other than a very slight advance and retreat of the poles) about 5,000 years ago, but the second (B) and fourth (D) planets (the "Twins") circling Canopus, neither habitable, are much larger than Arrakis
The inner, Menaris, has a mean equatorial radius of 7,862 kilometers while the outer, Extaris, has a radius of 8,112 kilometers. Arrakis by comparison has a corresponding radius of only 6127.9621438 km (as of year 14521 AG). The Twins 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 the Twins, Arrakis achieves a highly eccentric orbit, maximum ellipticity 2.1, every 12323 years. The Twins also have a profound impact upon Arrakeen geology and tectonics. . Because of the large axial tilt, the polar axis of rotation processes a full revolution every 43,000 years.
The length of the year varies from 295 standard days to 595. By 14521 it is 353 days. When Arrakis is in its most elliptical phase, seasonal changes are extreme. Winters are extremely severe all over the planet. Throughout historical times, the orbit has been roughly circular, for the most part, with very little in the way of seasonal change. Only the geological record and theoretical calculations tell that conditions during the past were drastically different from those later.
The shortest days of record occurred from 12310 AG to 12420 AG with 5 nElroodim 12370 AG being the absolute shortest day, 5.28 hours long. The longest day recorded thus far was on 25 nAlraanim 15052 AG and endured 43.2 standard hours.
Arrakis had three natural moons, one was destroyed by impact from an on-rushing asteroid/comet; most of the debris impacted the planet's surface but a ring structure was formed around the planet. That moon lay in Arrakis's ecliptic plane and the ring of dust caused a major reduction in star energy striking the surface. Hence surface temperatures were reduced and an ice age occurred. Many life species perished while others assumed dominance. Perhaps oft-told legends refer to this event, and would place it at about 19,460 BG but geological data suggest that the event occurred at least 184460 BG.
The two moons Krelln and Arvon cause major changes in Arrakis's rotation about its own axis (the Twins also contribute, but their effects are longterm). Arrakis averages 22.4 standard hours per day. Theoretical calculations show that under special circumstances the day can be as short as 3.81572 hours and as long as 51.36405 hours. These changes in rotation rate, as well as the effects of Menaris and Extaris have had profound impact on the geologic evolution of Arrakis.
Arrakis has its own magnetic field caused by its fluid core in a mechanism not fully understood. This however is severely contracted by Canopus, which emits an abnormally high flux of charged particles with imbedded magnetic-field segments. As a result, particles impinge directly on atmospheric molecules. No known effect on Arrakis weather has been proven to be a result of this interaction.
Magnetic disturbances make the main field unreliable for navigation. Alternative means for direction finding, such as the paracompass, were developed to overcome this problem.
The sky had an almost uniform dullness due to light scattering by the dust although occasionally, more often in the polar regions, it often appeared bluish. Thin, cirrus clouds occurred seasonally in the polar vicinity.
Surface pressure, mean wind and temperature were also compatible with Neta 2C-53B guidelines: 1000 ± 5 millibars mean pressure, 286 ± 2 degrees absolute planetary mean temperature (annualized), and a mean global wind speed, standard height, of 20 ± 3 kilometers per hour.
The composition was quite similar to that of other Neta 2C-53B planets except that the amount of ozone was anomalously high and that of water vapor anomalously low. Ozone was concentrated only two kilometers above the surface produced by Canopus's strong ultraviolet flux and absorbed much of the flux.
Before Kynes' transformation, major gaseous constituents were nitrogen (74.32%), oxygen (23.58%), and argon (1.01%). The most important trace gases were water vapor (less than 0.5%), carbon dioxide (0.035%), and ozone (0.52%).
The excess ozone resulted to many atmospheric phenomena such as the Coriolis storm.
Considerable dust was present in the atmosphere at all times. The atmospheric dust content was within the bounds of the Neta 2C-53B classification.
Marta Ptahtercicah (AG 9527) investigated the mechanisms of water vapor transport in terms of the minimum amount required to sustain any life and the correctness was confirmed using Arrakis as the test case. A slight amount of water vapor transported between the poles during the seasonal exchange.
The climate over most of the planet was hot and dry. Sub-freezing temperatures occurred only at the poles. Nights were generally and relatively cool. When Arrakis is in its most elliptical phase, seasonal changes are extreme. Winters are extremely severe all over the planet.
An almost constant temperature difference (annual mean) of 27o C existed between the equator and the poles.
Dust clouds (and the generating storms) were naturally the dominant feature of Arrakis's weather. Dust was injected into the atmosphere as slender pillars by small vortex systems common to the desert portions of all Neta-class planets. They are caused daily by severe heating of the ground surface with cooler temperatures above and light wind. The hot air rose and pulled down the cooler air. The presence of a light wind was critical to me process since it was needed for the vortex to form. These phenomena ancient lore recognized as the spirits of ancestors.
These whirls do not present a hazard to humans. L.L. Nefad (9156 AG) simplistically proposed that the Coriolis storms (q.v.) were but a manifestation of the accumulation of multiple vortices associated with the turning of the wind vector by planetary rotation; Joon F. Hohshas (11301 AG) provided a better basis of understanding.
The dust whirls and storms generated considerable dust charging through friction making electrical phenomena an integral part of the environment: Lightning discharges occurred frequently within the clouds and occasionally bolts struck the surface. It was also a minor contributor to total atmospheric ozone.
Tiny grains (about sand sized) remained mostly in the lower levels of the Coriolis storms which caused severe erosion that in theory would erode all protrusions of the planet (if the planet were not so geologically active; see #Geology) consisting it totally flat.
When the storms decay, much of the dust settled back onto the surface. Water vapor absorbed on the grains was carried downward also (a phenomenon locally called El-Sayal). Ionization by ultraviolet rays gradually released the water back to the atmosphere and return was complete within a few days.
Apart from the surface erosion from storms and the presence of dune fields noted above, other surface phenomena affected by weather, were the dust chasms (or tidal dust basins), areas of sand with quicksand-like behavior and the drum sands, a sound-emitting sand.
Arrakis, as a Neta 2C class planet, evolved after formation much as other planets of the classification. The oldest rocks on Arrakis have been dated, isotopically, as being 1.1 eons in age (1 eon = 1 billion standard years) These older rocks have been found only by deep drilling and furthermore have been located only in a few places, existing as small fragments contained in much younger rock. Almost all other planets of the same classification have rock exposed at the surface with ages greater than 2.1 eons. The evidence that geologic processes on Arrakis are much more dynamic in the destruction of ancient rock and the formation of new rock and surface features is thus convincing.
MorphologyEditThe first complete mapping and interpretation of the surface of Arrakis was done by Kynes in 10901 AG, who claimed to be an eighth generation descendant of Liet. The dramatic changes that have occurred since then were detailed by Xenach in 15029 AG. By then, many mountain ranges and deep valleys (grabens) existed in all regions of the planet, a situation similar to that of the earliest known phase of the planet's history.
One of the most interesting aspects of Arrakeen surface morphology is that the mountain chains and grabens run either north-south or east-west (geographic coordinates). This geometry is noted on a number of Neta-2C planets but never as clearly defined as on Arrakis. This geometry is intimately connected with the nature of tectonic processes on the planet
Arrakis is the most geologically active of all Neta planets and the rate of mountain building almost managed to keep pace with rapid erosion by sand blasting. After the terraforming of Arrakis which much-reduced the eolian erosion, and with little in the way of water erosion, mountains are rising "rapidly" (in a geological time sense).
During the middle phase, as existed during Kynes's time, extensive desertification had occurred with the earlier mountains had been severely eroded, primarily by sand blasting, and the surface was mostly flat except for isolated garres and ridges, a few volcanic peaks (such as Mt. Idaho, Mt. Kynes, and Observatory Mt.), and the dune fields. The planet is so geologically active that any elevation difference, other than the sand dunes, existed at all during the middle phase.
Mt. Idaho had been the highest peak. Its summit was 9,524 meters above the bled, compared to only 7,393 meters seven thousand years before that. Several mountain ranges had peaks exceeding 7,400 meters in elevation.
There are numerous deep valleys (grabens), the greatest of which is Grose Valen, with maximum depth of 1,250 meters, maximum width of 2,800 meters and a length of about 730 km.
During the desertification phase of the planet's history, most of these were filled with dust and called tidal dust basins or dust chasms by the natives.
The chasms provide much more of an obstacle to surface travel than the mountain ranges since they can be crossed only by very long and expensive bridges, and they expand and contract so rapidly that no bridge lasts very long. Hence most travel is by air.
Many of these had reopened through geological processes, and many more have formed.
The major grabens are not formed by running water; rather they are a result of the dynamic development of the planet. Filling of the chasms later resulted primarily from landslides and rockfalls.
Bodies of waterEdit
Few permanent rivers or bodies of standing water are present on Arrakis and drainage systems are poorly developed even after the ecological transformation completed by Leto II. Flash floods occur occasionally in mountainous areas, but all in all Arrakis is still quite water poor. Water ice is present in the polar caps, as is the case with all Neta-2C planets, but the total amount is small compared to that of other planets of the group. Garres are plentiful, and are easily distinguished by their flat tops. They are the oldest exposed areas on the planet, being remains of ancient plateaus formed by widespread lava flow very early in the planet's evolution when water was plentiful and water erosion dominant. Ancient water courses are still visible on their tops and their sides.
The small polar caps lie below bled-level. This "polar sink" is uncommon. The ice caps were much more massive in the distant past even existing as such during the early periods of human habitation (Hackelfhued).
Periodic episodes of ice advance occurred with massive glaciers and continental glaciation from the north polar cap extending as far south as 62° N latitude while that from the southern cap had furthest advance to 58° S. These massive ice movements from the poles scoured much of the rock in the polar areas, carried it to more temperate climes where the ice melted and deposited its mix of rock flour. The polar sinks were thus created.
Since the resulting ice caps exist in depressions it has been suggested that energy from Canopus be focused with large solar satellite arrays to form polar lakes. The water from these lakes would then be drained through tunnels to provide irrigation to those areas of Arrakis most in need of the water. Ghralic has provided compelling arguments against such a project, concluding that the present climatic balance on the planet would be seriously disturbed with possibly disastrous results.
Plate tectonics on Arrakis is caused by gravitational torques of Menaris and Extaris. The unusual closeness and large size of the Twins cause Arrakis to exhibit exceptional geologic activity. Quakes are common and the amount of volcanic activity is on the high side, but certainly not extreme. Portions of the crust are displaced with respect to other crustal segments by the astounding amount of 30 centimeters per year (planetary mean). New mountains are formed and old ones destroyed at a geologically rapid rate.
Over one 2,000 year period, the Tramblisch Range rose 3,125 meters. Grabens open, oscillate, and close at equally rapid rates. The north-south and east-west trends of all mountain ranges and grabens is a result of the particular geometry of the Menaris-Extaris-Arrakis system and stress-field orientation so produced.
Arrakis is a favorite planet for planetary geologists because one can literally see geologic processes in action with only a short time of observation. Mapping, however, is a problem and the planet is a civil engineer's nightmare.
The chemical composition of a planet depends upon its distance from the main star and that same planets consist primarily of silicates, some primarily of hydrogen (quasi-stars), some primarily of sulfides, while some are mostly metallic. The Neta class is defined specifically as comprising those planets with a composition of 60 ± 10% silicates (by mass), 30 ± 10% metals, 10 ± 5% sulfides and less than 5% hydrogen.
The crust and upper layers of Arrakis are composed almost entirely of silicates, the middle and lower layers are primarily silicates, but with significant amounts of metals and sulfides, while the core is primarily metallic with a small amount of sulfides. The precise chemical composition of Arrakis is 69.723% silicates, 21.388% metallics, 7.691% sulfides, and 1.198% hydrogen and miscellaneous.
The crust of Arrakis is rather thin, averaging only 10 kilometers in thickness. The source of volcanic activity is an incipiently molten region lies immediately below.
The remainder of the planet is basically solid except for a small, fluid central core which produces a relatively weak magnetic field. Even after many thousands of years of study the exact mechanism by which the magnetic field is produced was not fully understood.
Arrakis is the only planet in the system to harbor organic life forms. Life on Arrakis has been subject to harsh conditions during its history. It was discovered by the Society of Mystic Mariners under Jasta Mason.
The star nearest the north celestial pole is the + 9 magnitude star Yuspen.