Memory Alpha  Class D  36,770pages on this wiki Class D planet,
Emanations A ringed class D planet  In the Federation standard
system of planetary classification, a class D planet was
characterized as a small, rock-based body, such as an asteroid,
moon or other barren, cratered planetoid with little or no
atmosphere.  The planet known as Weytahn to the Andorians and
Paan Mokar to Vulcans is an example of a class D world. Weytahn
was class D before terraforming. It was described as being not
much larger than Earth's moon. (ENT: "Cease Fire") Regula, which
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