I just rolled up the most horrendous "habitable" planet ever.
 

Cauchemar: 0.35: Standard (Garden) 265 (BB) 61% hydrosphere, 1.01 density, 0.83 diameter (6,554 miles), 0.83 gravities, 0.57 mass, Thin Breathable Atmosphere (0.58 atmospheres), -0.4 eccentricity, 253 degrees (Very Cold), Perihelion 0.21, Aphelion 0.56. Tidal Force 3.1, 282 days per day, 107 days per year, 5 degree axial tilt, Light Volcanic Activity, No Tectonic Activity, RVM -1, Habitability 5

The "average temperature" is Frozen, but during its 9 and a half month long day the current day side really heats up, and every 3 and a half months it gets close enough to the sun to sterilize the tropical zone and boil the oceans.

It's the most uninhabitable habitable planet I've ever seen.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

I wouldn't consider it to be habitable at all. To my mind, a habitable world is one where humans (or whatever species) could, at least in theory, survive and reproduce open-ended without technological support (i.e. like Earth). I'm not sure TL0 humans could do that on this world.

(With the right technology and support, any world is potentially habitable.)

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Is generating a day longer than the year valid? I thought per the text on Space p118 that should be interpreted as tide-locked or perhaps resonant?
Without technological support is asking a lot..

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Reminds me of that planet from the old 2300AD supplement "Kafer Dawn" - tidally locked with the settlements on a thin equatorial belt, vicious tidal activity and a non-compatible biota.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Yeah, Habitable should be more "life similar to what we're used to can evolve here naturally." Many interpretations of how life would evolve elsewhere would, if using the definition of "Humans and similar can survive here without technological assistance," have only Earth as habitable - because we wouldn't be able to eat anything on a planet that evolved its own life. Here's an example from the recent Q&A for the webcomic Runaway to the Stars. Heck, you don't even need to go that extreme - in the web serial The Deathworlders, where everyone being able to eat each other's food is the norm (Earth crops become popular due to their high nutritional density compared to most others), a crew of humans get stranded on what is considered in-setting to be an extremely high-habitability planet (I think something like Class I or Class II, where most sophonts could be set down naked with no training or gear and thrive without issue), but the simple native plants are primarily cellulose (or at least a cellulose analogue), which humans cannot digest (the bulk of sophonts in the setting are herbivores and can digest it without issue), leaving them to starve once their food runs out (or it would have, if the Hunters weren't using it as a safari world to breed sophonts for eating; all the humans who survive to make it off-planet become strict vegetarians once they're back in human space, but while there they have no choice but to kill and eat other sophonts).

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Most of the problem, I think, is the eccentricity. Frozen happens, tidelocked happens, low pressure happens, but I think the eccentricity makes all of that except maybe the tide-locking irrelevant. This planet is probably something other than garden.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

It's an example of what GURPS Space calls a "changing world": specifically, one where "the world is subject to regular, cyclic changes in its environment," good for stories "emphasizing adaptability in individuals or societies." Another example is the planet Trenco from the Lensman series: during the day the surface boils to a gas; during the night it condenses into a liquid. To say it rains there at night is a massive understatement. The people who go there do so to obtain thionite, which is used to create a potent drug, and they go to great lengths to endure the changing cycles of the planet in order to get it.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

The eccentricity alone would not be that big a deal with a thicker atmosphere. It would just create rapid seasonal cycling with longer winters than summers. The eccentricity combined with days that last for months and the thin atmosphere creates gigantic cyclical temperature extremes,

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Cycle of Fire by Hal Clement has a planet with a long eccentric orbit so it changes every so many generations. So two seperate very different ecologies which in many cases are dormant spores or such in the other ecology lifeforms. So when it heats up enough the lifeform dies and the spores use the biomass to get a head start at growing.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Rotational period can't usually be longer than the year*, but the length of a day (synodic period) takes into account rotation and revolution around the primary. With Earth-like motion the effect is pretty minimal (Earth has a rotational period of 23 hr 56 minutes), but when rotation and revolution get closer, it gets more significant. Mercury has a rotational period of 58 earth days but a day length of 176 days (2 local years).

* Venus has a rotational period longer than its year, but it rotates backwards, so it isn't anywhere near tidelocking.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Aurora! Yes, excellent setting.

And of all things TSR's Star Frontiers had a world that completely froze at "night", with herd animals that migrated around the entire world to stay in daylight. I can't recall the name, though... Alcazzar? And Mutiny on the Eleanor Moraes was almost adequate.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Garden? I presume it has odd plants?

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Yeah, but I use it for a reason.

In principle, a viable human breeding population could endure indefinitely on Earth without any tools or equipment, just as other animals do. Fantastically difficult, yes, but possible. Allow simple TL0 tools and it becomes a very viable, in pure species survival terms. Earth is the only planet in the Solar System of which this is true.

If technological support is allowed, you have to draw a line to make the definition of 'habitable' mean anything. For a human population with access to high end (only modestly ahead of our own) space-flight level technology and a viable economic/industrial base, most planets are 'habitable'. For such a society, Mercury, Luna, Mars, the major asteroids, many of the big satellites of the gas giants, even the KBO worlds, are all 'habitable', in the sense that viable breeding populations could endure indefinitely on them. For slightly more advanced societies, even worlds like Venus and Io are 'habitable'. Advance the tech a bit more and the gas giants become 'habitable'.

Whether a world is classified as habitable or not depends on the metric.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Defining a boolean trait which only ever is false seems kind of pointless though.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

That is sooo true!

Re: I just rolled up the most horrendous "habitable" planet ever.
 

That is speculative and still the stuff of science fiction. No human has ever been born off the Earth's surface. The long term effects of low to no gravity on viable human development are unknown.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Trying to imagine how life could evolve there. It'd be constantly undergoing boom and burn cycles and have to find a way to cocoon.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

One think that habitable is can a average human produce enough wealth to produce the tech needed to keep an average human alive. We could build a Moon colony today but it would have to be subsidized.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Fair point. But even that is correctible by an advanced/large enough techbase/economy. Centrifuges can be built, for ex. It might never be practical, but it's possible in principle.

Which is my point, the boundary of 'habitability' depends on the technology and economy available.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

It isn't only ever false, though. Earth exists. It's the one definite True we know about, but it does exist.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Having the question "Is this planet habitable?" basically work out to be the same as the question "Is this planet Earth during the Holocene?" doesn't really accomplish much for you. Granted, a better question for the first one is "How habitable is this planet?" so that rather than a "Yes/No" answer you can have a range. A very habitable planet would be one where a person with minimal to no training could be dropped in naked and expected to thrive, this would progress into things being harder (needing more training and/or gear), eventually to the point of being largely indistinguishable from being a space habitat with more reliable gravity (and also progressing even further, with the habitat needing to be more resilient than a space habitat - like one in a gas giant or perhaps on a highly-volcanic planet).

Re: I just rolled up the most horrendous "habitable" planet ever.
 

I'm thinking migratory animal species predominate, while the plants have very durable seeds. The microflora and fauna would be able to cyclically produce extremophile offspring

Re: I just rolled up the most horrendous "habitable" planet ever.
 

There's the question of how life got started in the first place with the primordial soup getting boiled each season. Might it have originated underground, where it would be a bit shielded from the extremes? If so, you might have most life still being underground, but migratory plants and later animals might be able to survive on the surface.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Maybe it started out "normal" and then something happened to the planet to set it on its current orbit. If the effect wasn't cataclysmic, but gradual, life could have evolved to this point.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Kinda hard to imagine something less than catastrophic changing the orbit so drastically. I guess in theory you could have a lot of close passes by rogue planets (or even just other planets in the same system) that pull it a bit out of its original orbit each time until it's eventually in the crazy boom-or-burn orbit. That seems pretty low probability... but maybe no more so than life managing to evolve on a planet that always had such an orbit.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

It's a darn weird universe. Let's keep it that way.

Re: I just rolled up the most horrendous "habitable" planet ever.
 

Yes, it's going to be a range. One reasonable definition of 'habitable' would be something Anne McCaffrey expressed in the intro to one of her Pern novels:

That's a pretty good quick-and-dirty definition of 'habitable planet'. Of course it leaves lots of room for ugly surprises (and that particular planet held one in her story).

Re: I just rolled up the most horrendous "habitable" planet ever.
 

It's an old system. The planet used to rotate faster and the atmosphere used to be thicker.