May/June 2011 Lite Challenge Entry - Guinevere II-G Survey

So, I've finally decided to participate in one of these challenges; I've been lurking these forums for far too long. That said...

Hi everybody!

There's really not much story with this; I was focusing on practicing techniques rather than content . Though conceptually, this is intended to be a Heads-Up Display in a panoramic viewport aboard the vessel doing the survey (hence the wideness). There's still a fair bit more I intend to add, though I run the risk of the scene becoming too busy. And as much as I would like to, I may not add the foreground "window treatment," for fear of ruining it.

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Nice! Very good first entry; much better than mine :/

Way to jump right in! :)

very nice... and good to see another contestant jumping in :)

Well, I've added some more details, but my original concern about extraneous info overload may be coming true. Part of my issue is my interpretation of the contest goals; I chose to go with a snapshot from the vessel performing the planetary survey rather than a detailed survey report (so, it's more of a scene, than anything). Sure, it's kinda pretty, but is it faithful to the contest?

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This is really good. Nice Job. :)

I'm not trying to be a wet blanket, but I'll probably sound like one anyway.

According to your mass and radius data, Bittersweet should have a density of 0.64 g/cm^3. This is less than Saturn. However, as explained in this wikipedia article on gas giants:

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A cold hydrogen-rich gas giant more massive than Jupiter but less than about 500 M⊕ (1.6 MJ), will be just slightly larger in volume than Jupiter.[7] For masses above 500 M⊕, degenerate pressure will cause the planet to shrink.[7] Kelvin-Helmholtz heating can cause a gas giant, such as Jupiter, to radiate more energy than it receives from its host star.[8][9]

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The only exception to this rule is if the planet has a massive heat source. A planet can only get hot enough to puff up like this if (a) it is very close to its star, which is obviously not the case, or (b) it is fairly young, and still has a lot of heat left over from accretion. However, if the planet is too young, its moons would not have enough time to develop complex life. However, I don't know the math, so this situation could be possible.


Bittersweet's orbital period is also WAY too short. For a planet orbiting at 1.68 AU to have an orbital period of 1.33 years, its parent star would need to be almost 3 times as massive as the sun. Such a star would be something like a B8 or B9, and be about 70 times as luminous as the sun, and only have a lifespan of about 600 million years. This would have two main effects.

1. This star's habitable zone would be way out at 7-10 AU. Any life at only 1.68 AU would be fried.
2. Life would most likely not have time to even emerge, let alone evolve into a civilization, before the star blew up.

An orbital period of 2-2.25 years would be more reasonable, given that your planet should be near or a bit beyond the outer edge of the habitable zone. Alternately, you could keep your 1.33 year orbital period, but have Bittersweet orbit at only about 1.2 AU.

All the astrophysics stuff aside, you give the impression that this is supposed to be something you could see out of a spacecraft window. However, I took the liberty of making a computer model of Bittersweet and Garland using your statistics, and here is what I got: Attachment 36182

That's how big Bittersweet would look, assuming your ship was in a close orbit around Garland. The other moons would look even smaller.


Again, sorry if this sounds harsh or nitpicky. I'm just pointing out these errors as tips on how your entry could be made more scientifically accurate, since I have a feeling that accuracy could be important in this challenge.

Although this is not my entry I want to say thank you for putting in all the work in the above feedback. it's got me thinking... :)

Curse you and your wet blanketry, Omnigeek. But thanks.

Actually, it's as good a time as any to get the cold science down. Last night, I stripped away all of the display data to rework the important bits, so I might as well fold this in too. I had used some random online orbital data calculator and that's where I had gotten my numbers (the star was something in a class F at 2.65 solar masses, btw); and as we all know, there is no false information on the interwebs :twisted:. Really, I was just lazy and didn't bother to get a second opinion, or question my own sciencing.

And yeah, forget the window; guess I should go with a screen since that's really the only way to get a constrained field of view that would allow for a scene this populated. Actually, since it's in the future, nothing to say it can't be both a window AND a viewscreen.

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Originally Posted by walterful

Curse you and your wet blanketry, Omnigeek. But thanks.

Actually, it's as good a time as any to get the cold science down. Last night, I stripped away all of the display data to rework the important bits, so I might as well fold this in too. I had used some random online orbital data calculator and that's where I had gotten my numbers (the star was something in a class F at 2.65 solar masses, btw); and as we all know, there is no false information on the interwebs :twisted:. Really, I was just lazy and didn't bother to get a second opinion, or question my own sciencing.

And yeah, forget the window; guess I should go with a screen since that's really the only way to get a constrained field of view that would allow for a scene this populated. Actually, since it's in the future, nothing to say it can't be both a window AND a viewscreen.

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Glad to know I didn't come off as TOO annoying... XP

A 2.65 solar mass star sounds about right for the orbital period, although F class sounds a bit cool. My calculations gave me a temperature of about 10,000 Kelvins, which would be an A0 or B9. It's possible the star in the calculations you used was slightly off the main sequence.

Incidentally, I highly recommend using Universe Sandbox for creating realistic planetary systems (You can find it on Steam. I'm not sure what the price is, since I bought it before the Steam release, but probably between $10 and $20).
My planetary systems are all made using a combination of Universe Sandbox, Wikipedia, Gimp, and occasionally Wilbur (a Fractal Terrain generator).
I've also got a little tip for calculating the characteristics of your stars: for a star on the main sequence, these three equations should approximate its traits:

M= mass (solar masses)
L= luminosity (suns)
R= radii (suns. 1 sun= 0.695 M km)
T= temperature (suns. 1 sun= 5778 k)

L=M^3.9 R=M^0.8 T= (L/R^2)^.25
Simplified, the last equation is T=M^0.575

By the way, I'd like to ask some advice from you: how did you make the gorgeous cloud map on Garland. Don't worry, I won't use the tip against you in this contest, I'm too far in.