Eurydice and Deianira

[Zirojtan]

So like the person who opened a topic very similar to what I am about to present this is my first post on here. So I'll start by introducing myself:

My name is Nathan Matranga, I'm 21 years old, and I am a studying linguistics major with a specialization in Romance languages. I joined this website for the specific purpose of getting an opinion from the people on here about details that I have for the setting of a fantasy novel that I'm writing, since planetary science seems to be you guys' area of expertise. I've submitted this before in the Speculative Evolution forums on zetaboards without much luck. Most of the people there are young and more into evolving species than they are settings for the species to live, and those that are good with planetary science/climatology didn't take much interest in my project. I hope I can get some good pointers from you guys though, because from what I could see on the two year old topic I read with VERY similar questions to the questions I want to ask, you guys seem pretty good at this stuff. So here it is:

The world that I am building is called Eurydice. Eurydice thus far orbits an F7 Star called Radegast. Here is the Spectral Info:

Star Info:
Name: Radegast
Spectral Class: F8
Mass: 1.190
Radius: 1.260 AU
Surface Temperature: 62000 K
Luminosity: 1.93
Habitable Zone: 0.9797 AU-2.438 AU

The older topic to which I'm referring was asking about the color of photosynthetic plants on a planet that orbits an F star. From what I gather from reading on the internet, plant life on such a planet might prevail in different shades of blue, with a mixture of red/orange. If I'm wrong I'm definitely open to correction. I'm more interested though in effects on the tectonics/tidal forces/climate of Eurydice based on her unique attributes. So here's the planetary info:

Planetary Info:
Name of Planets: Eurydice
Distance from Star: 1.6776 AU
Length of Year: 2.001 Earth Years
Number of 24 hr days: 728.5
Number of 62 hr days: 282.75 (every four years is a leap year by 3 days)
Radius in km: 6,318
Axial Tilt: 22
Mass: 6.60385e24 kg (1.1055 E mass)
Volume: 1.1006e12 km (1.01609 Earths)
Density in Grams: 6 g/cm3
Diameter: 12810
Surface Area: 515.9
Roche Limit: 1700
Gravity: 1.09487 Gs
Orbit Velocity: 8.29 km per second
Thrust to Orbit Time at 3G: 7.3
Escape Velocity: 11.7 km per second
Geosynchronous Orbital Distance: 75780 (from surface of planet)
Geosynchronous Orbital Velocity: 2.31 km per second
Mean Kelvin Temperature:
Atmosphere Composition:

As you can see I don't have a Mean Kelvin Temperature or an Atmosphere Composition yet. This world is supposed to be inhabited by human beings though as well as tetrapod life introduced during the world's creation by a divine entity descended from Dipnorhynchus-like ancestors. The creation myth isn't really important for this discussion though... Originally Eurydice was also supposed to have an axial tilt of 80 degrees. The trouble was making it habitable for life with such extreme seasons, and once it was presumably possible the stable climate areas for civilization were rather limited, meaning limited cultural diversification with only a few areas that people can inhabit, which is something I didn't want. I chose an axial tilt of 22 degrees because while I liked wacky seasons, I realized that they might pose extreme obstacles for complex agricultural societies, and I'm looking for something a little bit more temperate and less tropical (I read that higher tilts might expand tropical zones). But another very important factor is Eurydice's natural satellite. Eurydice is supposed to be a part of a double planet system, tidally locked to an icy planet called Deianira. Besides a mass of 6.57096e24 kg (1.1 Earth masses), a volume of 1.0109e12 km3 (0.93326 Earth volumes), a density of 6.5, a gravity of 1.15348 Gs, a radius of 6226 km, and a distance of 103.5 thousand kilometers between the two planets, there isn't much information on Deianira other than that she's an ice ball.

I had also theorized that there were originally two moons orbiting Eurydice, Deucalion and Pyrrha that wandered into her Roche Limit and now form rings of dust and debris... not sure how realistic that is though.

With these specific conditions I'm having a lot of trouble drawing myself a map for this world, or describing its features.

What are Deianira's affects on Eurydice's climate, gravity, tectonic activity, and tidal forces? How does the distance from the sun affect climate features such as the wind, and general heat?

I have also been trying to find a reason to make the sky orange... not sure how I'm going to do that and preserve a temperate climate though.

I have a map of continental shapes on Eurydice almost finished. Is that something you guys would need to see?

Any help would be greatly appreciated.

[ryacko]

Radius: 1.260 AU

Distance from Star: 1.6776 AU

Uhm. It's orbiting inside the star? Unless you mean it's distance from the surface of the star... the star's radius seems a bit big as well.

Originally Eurydice was also supposed to have an axial tilt of 80 degrees.

Actually it wouldn't have extreme seasons. It would be de facto tidally locked, and likely would have strong winds to redistribute heat.

I have also been trying to find a reason to make the sky orange... not sure how I'm going to do that and preserve a temperate climate though.

Change the cones of the eyes of the local sentient life?

[Zirojtan]

I meant in distance from the star, yes...

And de facto tidally locked to what? As far as I know the planet isn't tidally locked to anything but the other planet, Deianira.

[fuzzymillipede]

How is Deianira an ice planet when it is roughly the same distance from the star as earth-like Eurydice?

[Zirojtan]

Hmmm I forget why... my friend and I had a good explanation for this though. I believe it had something to do with her atmosphere.

[Ziggy Stardust]

While I appreciate how thorough you are, for the purposes of your story, how much of this is really important? I mean, if you are setting the story on another planet it certainly is nice for it to be plausible, and it definitely is worth pursuing elements of scientific plausibility, but it is also important to remember that all of this comes second to the story.

What story are you trying to tell? What sort of civilizations/flora/fauna/environments/etc. do you want in this story? It will work far better going backwards; that is, decide what you want at the end, and figure out what set of conditions could plausibly make those exist. I understand that is probably the thought process that led to the figures you have above, but again ... why do you need them? A good story teller isn't going to be telling the reader what the orbital radius of the planet is and all of that. By getting too detailed with the background fluff, you run the risk of falling into the trap that many aspiring sci-fi/fantasy writers fall into: they become too obsessed with showing off how well thought-out or how original their world is as opposed to telling a story, and the novel suffers.

Just ... you know, keep your priorities straight. When you are dealing with speculative science (life on other planets, etc.), having the exact numbers isn't even helpful anyway. What does it matter what the mass is down to 8 significant digits? The qualifying factors are more important in this case than the quantitative. What I mean by this is that the exact mass is irrelevant, for the purposes of creating a world you are only interested in how the mass effects surface gravity and other factors; so, "high" vs "low" vs "medium" as opposed to "6.000283123834" vs "6.223231423434".

[Zirojtan]

Well you are correct to assume that that kind of thought process is what has led to the above figures.

I'm well aware of what kind of societies/flora/fauna I'm after for the books. I also have a pretty good idea of how the story plays out, and know very well that very little of this actually affects the story at all. I know that an info dump as to the biological details of the setting will discourage any reader, especially in today's fast paced society, from my books. I guess this has everything to do with drawing the map... without a map to relate the concept of location, I'm having a lot of trouble writing anything at all. In order to draw a map though, I don't want to just arbitrarily put forests here and there like some very famous worldbuilders have in the past. I admit, I'm really anal about unnecessary details that most readers don't care about, but since I belong to a minority of readers that DOES care about this kind of stuff, I think that it's hypocritical of me to criticize Tolkien's Middle-Earth for lack of attention to detail and then go off and commit the same sin.

The kinds of cultures I'm looking for probably a little bit removed from your typical fantasy fiction society.I have definitely tried to get away from the typical Euro-centricism. As far as the fauna is concerned though, I have stayed married to the idea of tetrapod, mammal analogues being the dominant group on land. The reason for this has been because while I would like to get away from traditional assumptions ("they have sheep, just like us!), I want the life to be relatable enough to something you might encounter on Earth that the reader won't get lost in the description of a wildly divergent form of life. For example, trying to incorporate something as complicated and odd as the fauna of the Snaiad Project. So different, but relatable is the general idea here.

The majority of the planetary info is really just going to go in appendixes at the END of the book that would help to explain minute details or allusions to worldly differences that pop up in the story.

The point is... I know very well that I can't incorporate A LOT of these kinds of details into the story. I will bore my readers to death if I go into a detailed description of the history of agriculture in the Prassian Basin. I just want to be able to know a little bit more about the setting, mostly for ME, so that it can be real to ME, so that I can then consider how that setting affects the story.

[Junghalli]

How is Deianira an ice planet when it is roughly the same distance from the star as earth-like Eurydice?

Less greenhouse gasses in the atmosphere would be the obvious possibility. Once it's in a snowball state the higher reflectivity of ice vs. land and water would also cool it down.

[starslayer]

Question that nobody seems to have noticed: why are you putting your planet 0.4 AU away from the surface of an F giant? That would make the surface closer to a lava sea than a water ocean.

Also, what units are the star's mass and luminosity in? I suspect solar units (and you may have meant that for the stellar radius instead of AU as well), but it'd be nice to have confirmation.

[Zirojtan]

Sorry, I wrecked on my bike yesterday and I'm kind of in some pain right now... it happened at the very beginning of the ride, and I swear it didn't hurt that bad until about 3 or 4 hours after I got home. My hip is all swollen and my head hurts pretty bad...

Anyways,

I'm not sure I understand the question? Eurydice is 1.67 AU away from the surface of Radegast.

And I believe solar radius is the correct unit of measurement. I made these calculations back in March I think using the calculators available on this website which has recently become available again: http://www.world-builders.org/, but more specifically on this page, so I guess Radegast is an F8, I forgot... http://www.world-builders.org/lessons/l ... hoose.html

To tell the truth I'm not sure what units of measurement he's using a lot of the time, he just compares it to the units of our own sun, so I can only assume we're talk solar units...

[The Romulan Republic]

Sorry to go off topic here, but given your description of your injuries, I strongly advise you to seek medical treatment immediately. Head injuries are not to be taken lightly.

[Zirojtan]

I would love to. But I live in a rather isolated location on the Big Island of Hawai'i, and the car is broken down. Unless you have $2,000 for an ambulance, I'm not going anywhere for now.

Anyways I think I'm satisfied with the map. Should I post it? Or should I wait for more input on the effects of the duel-planet system on the plate tectonics?

[Zirojtan]

Hmmmm I can't edit my post...

Well I hate to double post, but I've been reading about the composition of our atmosphere, and given that Radegast of a brighter star class than Sol, would I not have to thicken the ozone layer to prevent dangerous UV radiation from getting to the surface of the planet?

[Simon_Jester]

Just ... you know, keep your priorities straight. When you are dealing with speculative science (life on other planets, etc.), having the exact numbers isn't even helpful anyway. What does it matter what the mass is down to 8 significant digits? The qualifying factors are more important in this case than the quantitative. What I mean by this is that the exact mass is irrelevant, for the purposes of creating a world you are only interested in how the mass effects surface gravity and other factors; so, "high" vs "low" vs "medium" as opposed to "6.000283123834" vs "6.223231423434".

This is a stupidly common problem with people who know the equations (or have a 'wizard' program to do it for them) but don't have a good sense of what the underlying numbers mean: they just copy-paste as many digits of a number as their calculator can hold, without thinking about whether it matters to report the eighth decimal place.

[Junghalli]

Well I hate to double post, but I've been reading about the composition of our atmosphere, and given that Radegast of a brighter star class than Sol, would I not have to thicken the ozone layer to prevent dangerous UV radiation from getting to the surface of the planet?

This seems relevant.