The Continuity Guide
Alien Planets
by Martin Willey

17 Alien Planets

The first alien planet encountered by the Moon was Meta (above), which was passing through Earth's solar system (this is not clear in the episode). During the six years of travelling through deep space, the Moon passed 22 planetary systems. In order, these planets were:

#	Planet	Days since Breakaway	Interval	Episode
1	Terra Nova			Matter Of Life And Death
2	Earth			Another Time, Another Place
3	Zenno			Missing Link
4	Piri			Guardian Of Piri
5	Ariel			The Last Sunset
6	Atheria			Collision Course
7	Ultima Thule			Death's Other Dominion
8	Retha			The Full Circle
9	War Games planet			War Games
10	Betha & Delta			The Last Enemy
11	Arkadia			The Testament Of Arkadia
12	Psychon	342	Average 31 days between systems in Year 1	The Metamorph
13	Vega	515	173 days since Psychon	One Moment Of Humanity
14	All That Glisters planet	565	50 days since Vega	All That Glisters
15	Luton	892	327 days	The Rules Of Luton
16	New Earth	1095	203 days	New Adam, New Eve
17	planet D	1150	55 days	Brian The Brain
18	Chrysalis planet	1288	138 days	The A B Chrysalis
19	Sunim	1702	414 days	A Matter Of Balance
20	Tora	2012	310 days	The Seance Spectre
21	Ellna	2306	294 days	Devil's Planet
22	Immunity Syndrome planet	2310	4 days since Ellna; average 179 days interval in Year Two; 105 days in both series	The Immunity Syndrome

In Matter Of Life And Death, Kano estimates that the Moon will pass by 10 million planets in 2543 years, including 3600 Earth-type planets. That's a solar system every 11 days, with an Earth-type planet every 8 months. The actual rate was ranged from over a year (between the The A B Chrysalis and A Matter Of Balance), to just 4 days pass between the planets in Devil's Planet and The Immunity Syndrome. To help the Moon on it's way, there were unexpected black suns (Black Sun) and space warps (twice in Another Time, Another Place, once in Collision Course, once prior to The Metamorph, once in Space Warp).

Among the planets were ice worlds (Ultima Thule & Vega), desert worlds (Tora, All That Glisters planet), forested Earth type planets (Retha, Sunim, Luton, Ellna, New Earth, The Immunity Syndrome planet), dead worlds (the war-blasted Betha & Delta, volcanic Psychon, Earth in Another Time, Another Place, Arkadia) and a few more bizarre environments (Piri, Zenno). Almost all have oxygen atmospheres; the exceptions are Kreno and the Chrysalis Planet (both chlorine), planet D, and Tora.

The vast majority of alien species are humanoid (perhaps all descended from the Arcadian exodus from their dying world). Some humanoid species have distinctly alien features, notably the coneheads from War Games and the captured aliens on Psychon and Luton. A few non-humanoid aliens are seen: the dragon from Dragon's Domain, Maya's rubber suit monsters, the globs in The Bringers Of Wonder, the trees from Luton and the rocks from All That Glisters. There are also an assortment of aliens who have no physical form: the "I" entity in The Immunity Syndrome, the Zoref entity in Force Of Life, and the visitors from Triton. We never find out what the aliens from Ariel, Kalthon, Piri or Jarak's world look like.

Only a few aliens are not oxygen breathers: the chlorine breathing chrysalides are remarkably humanoid but must be radically different biologically; the Kreno animal is also a chlorine breather; the globs from The Bringers Of Wonder do not require any atmosphere; and the Psychon animals seen in Space Warp and The Bringers Of Wonder store oxygen when on the lunar surface. A surprising number of planets seem to have tiny populations: Zenno (3), Betha (5) & Delta (1), the War Games conehead planet (2), Psychon (2), Golos (3), the Chrysalis planet (4). Most are more advanced than Earth, notably Atheria in Collision Course and Zenno in Missing Link.

Four federations of planets exist: Croton, Sidon, the Dorcon Empire and Taybor's Trading Worlds. Triton, Betanon and the Archanons also explore space extensively. Psychon has had contact with the Dorcon Empire and the Trading Worlds, as well as a number of other planets such as Kreno and Archanon.