- "...cloaking technology which renders them invisible to the naked eye, and to Wraith scans."
- —Radek Zelenka
A Cloak is a device that allows an object to become invisible, either to the naked eye, sensors, or both. They exist in varying forms and sizes to cover either a single person or whole ships.
Cloaks by cultureEdit
The Ancients employed cloaking devices in all of their Puddle Jumpers, which could be interfaced with the shield of Atlantis to cloak the entire city, a tactic that was used numerous times to hide the city from the Wraith. It is probable, therefore, that all Ancient vessels can be cloaked in a similar manner. Ancient cloaks render the ship invisible to the eye and all forms of sensors whilst using very little power. However, the use of the cloak negates any shielding the vessel may possess. Ancient cloaking technology is superior to that of the Goa'uld, as ships using an Ancient cloak cannot be detected while entering a planet's atmosphere, while Goa'uld vessels can be detected through heat buildup during reentry. The cloak is not infallible, however, as a hive ship equipped with a Zero Point Module gained enough sensitivity in their sensors to detect cloaked Jumpers, albeit not with perfect accuracy. (SGA: "Rising", "The Siege, Part 3", "Progeny", "Enemy at the Gate")
The Asgard use invisibility devices, which are applied to the body of an individual and then activated. These devices were used by the people of an Asgard protected planet to hide from predators. The Asgard also employed a sophisticated form of cloaking technology in all Bilskirnir-class ships to mask their presence from all manner of scanning devices, including radar. The Tau'ri had no way to detect its presence, which suggests it might be capable of disguising itself from visual identification, as well, though this is not made clear. (SG1: "Shades of Grey", "Fair Game", "Nemesis")
AsuransEditAsurans were able to perfectly copy Ancient technology, they also had access to their cloaking technology. Their only known use of such a technology was on their cruisers and Puddle Jumpers. (SGA: "Lifeline", "This Mortal Coil")
Goa'uld Tel'tak and Al'kesh can be cloaked, and there has been one extreme case of Apophis cloaking an entire fleet of Ha'taks. Given the rarity of the latter, this would seem to imply that the technology requires a lot of power, or at the very least has size limitations which cannot be easily bypassed. Goa'uld also make use of personal cloaking devices. Any Goa'uld ships passing through a planet's atmosphere whilst cloaked will give off a heat signature that can be detected by other ships. (SG1: "Fair Game", "Deadman Switch", "The Serpent's Venom", "Exodus", "Last Stand", "Allegiance")
The Nox are apparently able to cloak both themselves and others naturally, which they have trouble maintaining while resurrecting someone. In addition to making objects invisible, they also seem to render objects intangible; an arrow fired by Colonel Jack O'Neill at Apophis, which he could not feasibly have dodged, simply went right through where he was standing after the Nox made him vanish. Though they can hide things around themselves, their city was cloaked by a special cloaking device. (SG1: "The Nox", "Enigma", "Pretense")
The Sodan use personal cloaking devices built according to Ancient instructions. These have the unusual property of allowing the user to see (but not otherwise interact with) out-of-phase matter. They also emit radiation meant to block the appearance of worm-like extra-dimensional creatures. (SG1: "Babylon", "Arthur's Mantle", "Uninvited")
While the Tau'ri do not possess conventional cloaking technology, the Odyssey acquired the ability to cloak thanks to Dr. Daniel Jackson when he used Merlin's Ancient knowledge. He claimed that "having a ZPM helps", so it is possible that he utilized the ZPM on the ship in some manner while creating its cloak, or that it was not as efficient as those on other ships and required levels of power only a ZPM could provide. (SG1: "The Shroud", "Dominion")