Small worlds with atmospheres

[mike wightman]

It appears that small worlds with atmospheres may not be all that difficult to explain after all.
Here's the link

 

[RainOfSteel]

And the article leads off with: "its gravity is too weak to hold on to an atmosphere for long so it must be being replenished."

 

[Golan2072]

Also remember that temperature effects the chances of the atmosphere's escape. Titan has quite a thick methane atmosphere, even though it's quite a small moon, since it's in the frozen reachyes of the Saturn part of our solar system.

 

[RainOfSteel]

Originally posted by Employee 2-4601:
Titan has quite a sick methane atmosphere,

The question then becomes, will science ever be able to cure the sickness of methane?

Originally posted by Employee 2-4601:
even though it's quite a small moon

Titan? Small?

</font>

• Titan's Diameter: 5150 Kilometers</font>
• Ganymede's Diameter: 5262 Kilometers</font>
• Luna's Diameter: 3476 Kilometers</font>
• Enceladus's Diameter: 498 Kilometers.</font>

Titan is the second largest moon in the solar system.

The first three qualify as Size 3 and 2 worlds.


Data Source: www.nineplanets.org

 

[Golan2072]

Thanks for locatying my typo - I was typing this while still groggy from my night's sleep.

Sure, Titan is a large moon; but it's still a small world.

 

[RainOfSteel]

Originally posted by Vhela Psylocin:
If you are concerned about small diameter worlds holding an atmosphere, it must be either replenished somehow, or there is a very dense core providing excessive gravity for it's size.

CT used Earth density (5.5 g/cm, I think) as a relative constant regardless of size. Doesn't book 6 have options for determining world density and gravity as a %age of Terran norm?

But you can only specify such a thing, reasonably, so many times. The UWP data available (though it's a combination of a big canonical mess, and ane even bigger non-canonical but-much-used mess), such as it is, probably contains over a thousand such requirements.

Here are a couple of excellent UWP discussion references:
</font>

• UPP, the very best</font>
• Common Sense: Evaluating UWPs</font>

Badly Paraphrased from Return of the Jedi
And now you will witness the discussions of this fully armed and operational internet board!

<reaches over and clicks button on armrest />

Commit Topic Necromancy at will, commander!

 

[aramis]

Small worlds with atmospheres need either:
A) replenishment of atmosphere
B) heavy enough gasses for their size.
C) excessive gravity due to high-density

A and B are most likely. Probably in combination.

Even earth loses atmosphere to space. Mostly, earth loses hydrogen and helium...

 

[TheEngineer]

Hi !

Please note, that there is not "one" athmossphere
for one planet, but a series of different development steps and different athmos for a molten core planet over geological time.
So it may depend on the time frame in which you might catch the planet. Eg. protp-earths athmoshere was composed of CO2, water and nitrogen and oxygen free. The current composition is the result of several 100 million years of evolution, but is still changing...
Earths athmo will alter again and perhaps fade away after geological activity decreases...

I would catch up Aramis list and add "geologically active" and "replenishment faster as athmo loose", giving small one a chance for an athmossphere (but maybe not for a (geologically) long time.

Regards,

Mert