Miscellany

[stoutfellow]

1. It looks like we've got Murphy's skin condition licked. This afternoon the vet told me he needed to finish the course of antibiotics and vitamins, but I wouldn't have to bring him in again. He does look much better, and the bare spots aren't fever-warm any more.

2. I finally got Season 4.3 of Farscape, plus The Peacekeeper Wars. They weren't available last September, when I bought the rest of the DVDs; now I have the complete set. (And just in time; I'm about to start in on watching Season 4.2.)

3. On a related note, a bit of trivia: in the episode "Natural Election", the crew of Moya elect a captain. The voters are John, D'Argo, Rygel, Pilot, Aeryn, Chiana, Sikozu, and Noranti. There is one vote each for Scorpius (certainly cast by Sikozu), Rygel (presumably by Rygel), The Great Beyond or something like that (Noranti), and Aeryn, and four votes for D'Argo. I'm wondering who voted for Aeryn. Not Chiana - she's an almost certain vote for D'Argo. Probably not Crichton, given their estrangement at that point. I doubt that Aeryn would vote for herself, either. Pilot seems most likely to me - he's had a special bond with Aeryn since "DNA Mad Scientist". It's conceivable that D'Argo would be humble enough not to vote for himself, though. Any other Farscapers care to comment?

4. I just finished reading Vernor Vinge's Tatja Grimm's World, and something's bothering me. Among the key plot points are that a) the (Earthlike) planet in question is very low in metals and b) there is a high mountain range, one of whose peaks is high enough that the partial pressure of oxygen near the top is 0.7 PSI. Now, I'm not that knowledgeable about geography/geology, but that combination doesn't sound right to me - tectonics on Earth are driven by radioactive decay in the mantle, aren't they? The planet is part of a double-planet system, though. Could tidal effects substitute? Anybody know more about it than I do?

Comments

[pompe.livejournal.com]

Low-metallicity really doesn't mean "metals", it means anything heavier than helium, IIRC. So it isn't necessarily that that there's less metal on a world, it is perhaps more like less solids to build worlds of. Similarly less metals might mean smaller metal core, which may or may not influence the crust. It is a problem with the classic metal-poor SF worlds, the authors may or may not rationalize what metal-poor really means.

However, from a purely stable view I'm not sure if the situation above would work -I wrote about moons a while back. If the planet is locked at a forty hour orbit and solar tides act to despin the double planet to such a degree it actually generates a really serious amount of tectonic heating I'd guess the planets may well be doomed. The energy comes from a falling moon, in a sense. How big is the second planet? Big enough to also be Earth-like?

If I'd do a metal-poor world in the "no industrial revolution"-sense I'd choose a situation with more dead tectonics. Huge highlands and mesas, erosional features (and thus less oxygen with dying cycles). So the deposits are largely covered by a lot of sediment (or ice caps). There's no serious mining not because of a lack of metals, but because of a lack of ore to easily dig up.

[stoutfellow.livejournal.com]

Low-metallicity really doesn't mean "metals", it means anything heavier than helium, IIRC.

Sorry, I should have been clearer: the local astronomers had discovered via spectroscopy that the neighboring stars actually had much more metal - iron and copper were specifically mentioned - than their primary.

How big is the second planet? Big enough to also be Earth-like?

Yes; it appears to have life.

[pompe.livejournal.com]

Hmm. That's another classic which might be hard to explain by normal planet-forming scenarios.

I'd say in this case I would find it slightly hard to justify sufficiently strong tectonics - well, if they're Earth-like tectonics, they could be hot spot tectonics or maybe blob tectonics.

I presume the eclipse time only makes sense in the part of the world actually facing the other planet. Does the planet have seasons?

[stoutfellow.livejournal.com]

I don't see any explicit mention of seasons, no. (The locals do divide their year into quarters, for whatever that's worth.) The existence of eclipse time seems to suggest that the orbit of the twin planets about each other is at an angle to their orbit about the primary. If they're tidelocked, doesn't that imply that their axes are tilted relative to the ecliptic?

[pompe.livejournal.com]

Hmm. If there are eclipses every twenty hours of the local year, can the twin-planet orbit be much inclined to the planet-solar orbit?

[stoutfellow.livejournal.com]

Oh, I think we've crossed wires. Here's the relevant passage: "They were well into the eclipse season; once every twenty hours, Seraph blocked the sun or was itself eclipsed." I read that as saying that this pattern of eclipses occurs at certain times of year, not at all times.

[pompe.livejournal.com]

Yes, that makes much more sense. It is like Pluto and Charon. Still, the eclipse season would only make sense on part of the world.