In the fictional Star Trek universe, Qo'noS is the Klingon homeworld, also known as Kronos. Qo'noS is ruled by the Klingon High Command. The planet is green in color.
Around the 14th century, Qo'noS was invaded by the Hur'q.
Qo'noS suffered severe ecological damage with the destruction of its moon, Praxis, in 2293. This resulted in a much warmer climate. (The capitol city is shown to be snow-covered during the Enterprise era c. 2151, but is rather warm in the TNG era.) The planet was first visited by Humans in 2151.