Moon of Ithera · canyon desert · La Cicatriz Gemela
Selvane
In a nutshell
Selvane is the smallest and furthest moon of Ithera: a red canyon desert under a black sky, with almost no air. Ithera always hangs at the same point in its sky. It had water when it was young and lost it, and its cities are sealed, pressurised bases.
Selvane watches us map what she can never have.
What is Selvane like?
Selvane is the smallest of the three moons of Ithera, the temperate planet of the system. It is a lunar-type moon: dry rock, like Earth’s Moon.
- Size. 500 km in radius.
- Gravity. 0.42 m/s².
- Air. Tenuous: almost vacuum. It has only an exosphere, a very thin layer of argon and sodium.
- By day. The sky is black and the shadows hard. The red desert does not move, and the dunes are petrified in the sandstone.
- At ground level. Dust charged with static electricity floats. Against the light, the sodium leaves a faint glow on the horizon.
- Living there. Its cities are pressurised bases. Outside work means EVA, in a spacesuit.
Where is it?
Of Ithera’s moons, Selvane is the furthest out: 380,000 km from the planet. It takes as long to spin once as to go round (synchronous rotation), so it always shows Ithera the same face. From Selvane, Ithera is a disc of 1.812° fixed in the sky: it never rises or sets.
From Ithera, Selvane is just a point of light of 0.153°, pale at dusk. The line at the top of this entry is by Quill Sarn, the head of the Pathfinders, the explorers’ guild. Reya Kest, a young pilot of the guild, has heard him say it and adds:
“All I know is she’s beautiful and he’s right about nearly everything else, so I believe him on this too.”
Reya Kest, pilot
Near Selvane, in Ithera’s high orbit, runs the Relé Umbral: the system’s main node for communications and navigation. It is one of the strategic points the two sides fight over. The Armisticio de Ithera, the peace treaty, defines it as civilian precisely because it orbits so close to the neutral planet.
Why is its great canyon called La Cicatriz Gemela?
La Cicatriz Gemela, ‘the twin scar’, is Selvane’s great red stone canyon. From its floor, Ithera hangs in the sky. Somewhere on that disc lies the other one: La Cicatriz, the furrow left on Ithera by the Arca Aurora, a great ship that crashed there. The canyon looks up at it like a mirror. That is where the name comes from.
Why is it a desert?
Selvane had water in its youth, while gas was escaping from its interior. The salt flats, dry lakes and concretions date from then. Then it lost it. With an escape velocity of just 0.65 km/s (the speed needed to break free), it holds on to no air at all.
Its exosphere is topped up by a rain of micrometeorites, grains of rock from space. It is also fed by the sodium of its evaporites, the salts the water left as it dried.
What places does it have?
| Name | What it is |
|---|---|
| La Cicatriz Gemela | The red canyon, the most recognisable place on Selvane |
| Ciudad Albor | Desert city |
| Caldera Rescoldo | Geothermal city |
| Bastión Vigía | Mountain base |
| Sub-Base Calima 1 | Pressurised desert sub-base |
Posts raised later follow a custom for their names:
- A prefix for the type of place: Bastión, Sub-Base, Ciudad, Caldera, Cañón or Puesto.
- A word from a repertoire that mixes desert life with the memory of the system: Vigía, Atalaya, Calima, Salitre, Páramo, Solmera, Aurora, Armisticio, Compás, Sextante, Lastre, Fase, Tachadura, Fragua or Umbral.
What is odd about its orbit?
Selvane goes round Ithera in two hours. With the measured masses, the laws of orbital motion call for almost a month. It is the textbook case of why nobody works out trajectories from masses. Everyone consults the Tabla de Fases, the table of measured orbits.
Selvane closes Ithera’s 1:2:4 chain: it takes exactly twice as long as Tirane, and Tirane twice as long as Melvara.
