Irk

Irk is the homeworld of the bloodthirsty Irken race, and capital planet of the Irken Empire. The view of Irk from space is unknown to humans, but the capital city can be seen when Zim is rampaging through it in The Nightmare Begins when he mistakes Irk for an enemy planet. A screen showing the Irken Empire in the same episode depicts a large, dark blue planet in the middle, identified as Irk. This coloring was probably for easier identification for the Irken military audience, and Irk is believed to be red, magenta or pink in colour.