Irkens, Control Brains, SIRs Digestor




Irken imperial capital and native homeworld

Notable Facts

This is the homeworld of the Irken race, Irk has planetary rings.

First Appearance

The Nightmare Begins


Irk is the homeworld of the Irken race, and capital planet of the Irken Empire. Irk's appearance from space is unknown to humans, but the capital city could be seen when Zim was rampaging through it in "The Nightmare Begins", having mistaken it for an enemy planet. A screen displaying a map of the Irken Empire in the same episode depicted a large, dark blue planet in the middle, identified as Irk. This coloring was likely meant to highlight Irk for easier identification by the Irken military audience. Irk is believed to be red, magenta or pink in colour.

Physical Characteristics

Irk's climate, geography, flora, fauna and topography are unknown officially, though it is theorized that with the dominance of the planet by the Irken species, the entire planet has become covered in sprawling cities and metropolises, possibly even completely converted into a 100% mechanical/industrial world. There is even civilization deep under Irk's surface. The buildings in these cities are largely purple or magenta in color, reinforcing that it is an Irken custom to use shades of purple or magenta. The sky on Irk is light pink in color, much like on Foodcourtia and Conventia. The idea of rain puzzled Zim when he first saw it on Earth, indicating that there was no rain on Irk. In addition, Zim was unaware that staring at the sun from Earth causes blindness, implying that the star that Irk orbits is much dimmer than the Earth's sun or that Irk has a thick atmosphere or cloud cover that blocks much of the star's light.


The only known organisms of the planet are the Irkens themselves, the Digestor and the Control Brains, who dominate the planet in sprawling cities and metropolises. However, if Irk is or was anything like Earth, it will of course have other species native to it. Zim has made references to other species (Slorbees and Gasquiggasplorch, canonically) when speaking in metaphors, but it is not known if any of these creatures are native to his planet. Also, Irken Smeets are born presumably in a large "birthing facility" (known to be called the "Hatcheries", or, less commonly, "Smeeteries") beneath the surface of Irk. Very few Irkens are taller than five feet, except the Tallest and a few exceptions.

Canonically, Jhonen has not documented any flora native to Irk.


The idea of Irk being distant from its star would suggest the planet has a very low temperature. However, this does not increase the likelihood of water in the forms of snow, ice and rain, as water requires hydrogen and oxygen to be present on the planet, which Irk may be devoid of. However, this is again highly unlikely, since hydrogen is the single most common element in the universe, with oxygen being similarly common. Additionally, Irk's sun is presumed to have a very thick ozone layer, meaning that Irk must have oxygen in some form.


It has been confirmed that Irk has an atmosphere, since it has clouds and a pink sky, but the make-up of its air is unknown. It is presumed that it has contains a breathable gas also found on Earth, as Zim does not need his space suit to breathe on Earth. If this is true, it is conceivable that, conversely, humans can breathe unassisted on Irk.

It is suggested that Irk is rich in oxygen for it to be able to let the Digestor grow to such a tremendous size, similar to dinosaurs in Earth's distant past, it is also implied in "Walk of Doom" that Irk's sun does not emit ultraviolet rays, or that Irk's ozone layer is unusually thick, as Zim was shocked to discover that staring at the sun will blind you. However, in "Door to Door", Zim is plagued by the sun again, this time its intense heat assaulting him rather than his brightness. Zim complains that "even Sirius Minor didn't orbit such a horrible star" suggesting that the sun itself is more powerful, not that the atmosphere is thinner on earth.


Distance appears to be relative, changing for comic reasons quite regularly. Assuming that the conquered planet Conventia is anywhere near Irk, it takes about six months or less (depending on the speed of the ship) to journey from the Irken homeworld to Earth. 

Of course, that being said, it may also be possible that Irken ships cannot jump to hyperspace without a specific destination having been set beforehand, and as such, it would take much longer to reach a planet that one did not know the exact location of. Further evidence of this claim being the relatively short time it took Zim to reach Hobo 13 from Earth, as his ship was shown jumping to lightspeed.

Multiple galaxies near Irk and far from Earth were seen on the galactic map in "The Nightmare Begins", suggesting that Irk is not located in the Milky Way.


As seen on the galactic map in "The Nightmare Begins", Irk is surrounded by rings, meaning that it is likely high in gravity. However, unlike the ringed giants in Earth's solar system (such as Saturn and Jupiter), Irk is a solid planet like Earth and Mars rather than a gas planet. This is probably what gives Irkens their agility on Earth.

View from Space

As mentioned above, Irk's view from space is possibly unknown. However, in "The Nightmare Begins", Irk is said to be the dark blue planet with thin red rings in the center of the galactic map. We can assume that this is a color-coded representation of the universe, rather than its natural color, as all the other planets are a white color. Irk may most likely be red in colour as the color of the Irken sky is pinkish red similar to the martian sky.


  • "Irk" is also a synonym for "annoy".

Irk on the map

  • In "The Nightmare Begins", Irk can be seen on the map behind The Tallest. In this incarnation, it appears to be a blue planet with a red ring. However, this may simply be a color-coded representation, as none of the other planets surrounding it have any color and are left the same shade of light blue.
  • Irk was mentioned as a clue on the Earth television game show Jeopardy!.
  • In addition to his rampage in "The Nightmare Begins", Zim also caused massive destruction on Irk a few other times, as revealed in "The Trial" - shortly after being born, he caused a blackout that lasted 5 years, in an event known as "Horrible Painful Overload Day". Some time later, while trying to see the surface for the first time, he caused another blackout, which lasted 4 years this time, known as "Horrible Painful Overload Day part II".


See also