Dune Wiki
Dune Wiki
Nudune.png This article or section refers to elements from Expanded Dune
There are separate pages for this subject as it appears in the other canons, the reasons for this are explained here

"O Giedi Prime! Thy shades of black are beyond compare, from obsidian plains to oily seas, to the darkest nights in the Emperor's Eye."
Gurney Halleck[src]

Giedi Prime, later renamed Gammu, was the third planet orbiting the star 36 Ophiuchi B. It was the historical homeworld of House Harkonnen.


Geographic region of the planet

The planet's capital was originally Giedi City and the planet was ruled by a Magnus; security was maintained by the Giedi Prime Home Guard. Its capital under the Harkonnens was Barony (later Ysai). Another major city was Harko.

Giedi Prime had a day of length 31.27 standard hours and a local year lasting 2.6 standard years. The planet was of average temperatures and maintained a low level of photosynthesis. This low level of photosynthesis was largely due to the heavy industrialisation of the planet under the Harkonnens. However, the Harkonnens did maintain some of the planet's original forests, mainly of pilingitam trees for logging and export.

During this time the planet sported factories, arenas, and many cities. The arenas were used to hold spectacles for the populace, including gladiatorial events. During the rule of the Baron Vladimir Harkonnen, his nephew Feyd-Rautha would often perform in these arenas as a means for gaining popularity among the populace and the Houses Minor.


Giedi Prime was originally a member of the League of Nobles and was ruled by a Magnus. Shortly before to the Butlerian Jihad, the planet was ruled by Magnus Sumi. During the machine war of attrition, its defenses were to be equipped with Holtzman scrambler shields for protection from a machine attack. After the First Battle of Zimia, the League was alerted. The planet was the last inspection stop by Xavier Harkonnen; however his tiredness and his reluctance to return home perhaps paid a toll to the inspection.

The machines soon attacked the planet before the defenses could be completed; Agamemnon killed the Magnus and installed a copy of Omnius. During the occupation, Giedi Prime-Omnius decided to send probes with copies of himself to the furthest planets of the Known Universe. Soon after, Serena Butler assembled a strike team. With a blockade-runner, they infiltrated the defenses and reached the frozen poles of the planet and repaired the scrambler towers. This was coordinated to occur with a scheduled assault by the League of Nobles. The League forces were supplied with portable scrambler shields as well as a team of the Sorceresses of Rossak. Heoma destroyed Barbarossa in a suicide attack and left the Giedi-Omnius vulnerable.

Giedi Prime was also the place where the Jihadi forces returned after the battle of Peridot Colony.

Giedi Prime during Harkonnen rule

In the later years, the planet became the homeworld of the House Harkonnen.

The Change to Gammu[]

After the fall of the Harkonnens, administration of the planet was taken over by people of Caladan. During this time it was renamed by Atreides Warmaster Gurney Halleck into Gammu. It was an historical irony that Halleck would come to have power over Giedi Prime, as many years prior, he and his sister were slaves to the Harkonnens when they ruled there.

The Bene Gesserit had an investment there, which they had to write off as a total loss, and offset the cost by fees charged for services relating to the Star Jewel Project.

As part of Caladani (later Danian) administration of Giedi Prime (Gammu), most of the machines of industry were dismantled, and the planet's natural ecosystem was regenerated by large-scale replanting that lasted over thousands of years. Despite this however, some five thousand years after Harkonnen rule had ended, oily residue could still be found in the planet's soil.

Eventually, much of Gammu came under the control of the Bene Gesserit Sisterhood. It became the base from which they grew Duncan Idaho gholas for their breeding programs. However, many parts of Gammu's cities were also under the control of Houses Minor and organisations returning from The Scattering, organisations that had managed to amass significant wealth. Indeed, Gammu appeared to become a popular destination of people returning from The Scattering, and upon their return they brought with them many new and strange customs that found a home there.


The Harkonnen military forces were conscripted from the general populace of Giedi Prime. These forces were fairly effective because many of them had managed to channel their oppressed upbringing into military endeavours. Indeed, much of the planet's population lived a meagre and oppressed existence due to the harsh rule of the Harkonnens. Many natives of Giedi Prime were used as slave labour to work the machines of heavy industry that occupied so much of the planet's surface.

Behind the Scenes[]

The name "Giedi Prime" is thought to derive from the Arabic phrase al-Jadii.