Memory Alpha
Memory Alpha
Class D planet, Emanations

A ringed class D planet

For vehicle type, please see Class D loader.
"Essentially a great rock in space."

In the Federation standard system of planetary classification, a class D planet was characterized as a small, rock-based body, such as an asteroid or other barren, cratered planetoid with little or no atmosphere.

The planetoid known as Weytahn to the Andorians and Paan Mokar to Vulcans was an example of a class D world, though the Andorians terraformed it to have a breathable atmosphere. It was described as being not much larger than Earth's moon, Luna. (ENT: "Cease Fire")

Regula, which in 2285 was described as a "great rock in space" with a few "unremarkable ores," was also a class D planet. (Star Trek II: The Wrath of Khan)

In 2371, the USS Voyager found a ringed planet in the Delta Quadrant which was also class D. Some of the asteroids comprising the rings were big enough to have class M environments inside them. (VOY: "Emanations")

A subspace sinkhole encountered by the Voyager in 2375 led to a subspace pocket, where a star system composed of a G-type star and three planets was located. One of these planets was class D. It was described as hot, arid, and rocky, but otherwise had an atmosphere breathable by humanoids, e.g., Humans and Vulcans. It also supported limited indigenous plants and a species of spiders. (VOY: "Gravity")

According to Star Trek: Star Charts, on page 23, a class D world had an average age of two to ten billion years, had a diameter of one hundred to one thousand kilometers, could be found in every zone of a star system, could be found in greater numbers around larger planets or in asteroid belts, had a barren and cratered surface, and had little to no atmosphere. An example given of a class D world was Luna.

List of class D worlds[]

Image Name Location Notes Source
Kerkhovian moon Kerkhovian moon In orbit of Kerkhov, Vulcan system, Alpha Quadrant Place of origin for the Kerkhovians SNW: "Charades"
Regula Regula Mutara sector, near the Mutara Nebula Star Trek II: The Wrath of Khan
T'Khut moon In orbit of T'Khut, Vulcan system, Alpha Quadrant SNW: "Charades"
Noss' ship crashed Unnamed subspace sinkhole planet Orbiting a G-type star, inside a subspace sinkhole in the Delta Quadrant Unusually hospitable for a class D world; destroyed when the sinkhole was collapsed by Yost in 2375 VOY: "Gravity"
Class D planet, Emanations Unnamed planet in the Delta Quadrant Delta Quadrant Asteroids in the ring system connected to Vhnori homeworld by subspace vacuoles VOY: "Emanations"
Weytahn Weytahn/Paan Mokar Andorian-Vulcan border, Alpha Quadrant Terraformed by the Andorian Empire in the 2050s ENT: "Cease Fire"

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