STAR CHART: PLANETS -
PLANETARY CLASSIFICATION - D, E, F

Class-D examples mentioned in the above STSC illustration: the Moon (Sol IIIa), Lunar V (Bajor VIIe). The Moon is Earth's natural satellite (in the last decade of the 20th century, another moon was discovered but this is not mentioned in any Star Trek). The Moon was the first world visited by Earth space explorers, [TOS: Tomorrow is Yesterday], and footage of the historic 1969 landing on the Moon is seen in [#117 11:59] when Shannon, Kathryn Janeway's ancestor, dreams about it. In the 24th century, 50 million people lived on the moon that was home to Tycho City, the New Berlin colony, and Lake Armstrong; and on a clear day, one could see Tycho City from the surface of the Earth; noted in [Star Trek VIII: First Contact]. One of the Valiant's crew was a native of Tycho City, [DS9: Valiant].

[#117 11:59]

At night Shannon dreams about the first moon landing in 1969 and the historic words of Neil Armstrong as he descended onto the moon's surface. "Roger that, and go ahead." "That's one small step for a man, one giant leap for Mankind."

[#117 11:59]

Class-D planets are small, rocky planetoids. An example is Regula, a Class-D world in [Star Trek II: The Wrath of Khan].

[#9 Emanations]

The ringed Saturn-like planet in [#9 Emanations] is also described as a Class-D world, but the term had previously been established to describe asteroids, and [DS9: Starship Down] further establishes Saturn to be a Class-J planet. Perhaps the Voyager crewmembers refer to the asteroid-like objects in the planet's rings, or maybe they are just overly excited at the discovery of element 247. Janeway: "Captain's log, stardate 48623.5. There are 246 elements known to Federation science. We believe we have just discovered the 247th inside the ring system of a class-D planet."

Class-E example mentioned in the above STSC illustration: Excalbia is an uncharted planet whose surface is molten lava and the atmosphere poisonous. The Starship Enterprise NCC-1701 visits there in 2269. The lifeforms indigenous to Excalbia are rock-based, intelligent entities who possess ethics and values very different from those of many humanoid species. They are intensely curious about other lifeforms and have captured such specimens in order to observe their behaviour in dramatic situations created by the Excalbians. They are shape-shifters and used their ability to alter their molecular form to remake themselves into characters to support such dramas. One such experiment, conducted in 2269, involves the capture of the captain and first officer of the Enterprise NCC-1701 (Kirk and Spock). They are placed into a conflict with various historical figures including Abraham Lincoln, Kahless the Unforgettable, and Surak of Vulcan (click link for picture). [TOS: The Savage Curtain]

Class-F example mentioned in the above STSC illustration: Janus VI - the STSC illustration incorrectly notes it as "Janus IV", so I amended the illustration. Janus VI is the homeworld of the Horta, a civilisation of intelligent, silicon-based lifeforms. Janus VI also contains rich deposits of the mineral, pergium, and the Federation has a pergium production station located underground on the planet. (In 2373, in [#55 Fair Trade], the USS Voyager crew visit the Nekrit Supply Depot in the Delta Quadrant seeking to obtain by trade pergium among other things.) In 2267, prior to first contact between the miners and the Horta, several mining personnel were killed under mysterious circumstances. It turns out that they were killed by the mother Horta attempting to protect her children. Once contact was made, and the miners learned not to endanger the Horta eggs, peace is restored. Not only that, but an understanding seems to have been made that the Horta would aid the miners because for the Horta tunnelling is effortless by comparison to the effort needed by the miners. [TOS: The Devil in the Dark].