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<blockquote data-quote="Warehouse23" data-source="post: 2331233" data-attributes="member: 27941">As far as producing a Mars-like world goes, here's some things to think about:* Mars and Earth have very similar axial tilts (at present) (25.2* versus 23.5*).* The technical term for axial tilt is &quot;obliquity.&quot;* Mars, unlike the Earth, has experienced rapid changes in obliquity over the past millions to billions of years. The moon keeps Earth's obliquity to within +/- about 5* of its current state. Lacking a large moon, Mars' obliquity has varied between 0-90* obliquity during its existance, and likely, as much as 0-60* within the past several million years (all these calculations are statistical, as the fine dynamics of planets is still something which is rather difficult to compute).* There is a lot of discussion in the Mars community over what the planet was like during past periods of high obliquity. When the poles face the sun for large portions of the year, volatiles, such as water and C02 seem to migrate towards the equator, which is largley in shadow at high obliquity. Exactly how quickly the polar ice deposits collapse and migrate is still not well constrained. This makes for a nice backdrop to gaming, though, if you want your world to be suffering from sudden droughts and floods in unpredictable ways. * Just a reminder: seasons are a function of a planet's obliquity. At present, the northern hemisphere of Earth is actually closer to the sun during winter than during summer. It's just angled at such a way that the sun is lower in the sky, producing less intense radiation on the surface (in Watts/square meter) which produces the cold season. At 0 obliquity, &quot;seasons&quot; would be driven by eccentricity (the degree of circularity of the planet's orbit). Although there are eccentricity effects on climate (on Earth and Mars), seasonal variation is dominated by obliquity.</blockquote>

[QUOTE="Warehouse23, post: 2331233, member: 27941"] As far as producing a Mars-like world goes, here's some things to think about: * Mars and Earth have very similar axial tilts (at present) (25.2* versus 23.5*). * The technical term for axial tilt is "obliquity." * Mars, unlike the Earth, has experienced rapid changes in obliquity over the past millions to billions of years. The moon keeps Earth's obliquity to within +/- about 5* of its current state. Lacking a large moon, Mars' obliquity has varied between 0-90* obliquity during its existance, and likely, as much as 0-60* within the past several million years (all these calculations are statistical, as the fine dynamics of planets is still something which is rather difficult to compute). * There is a lot of discussion in the Mars community over what the planet was like during past periods of high obliquity. When the poles face the sun for large portions of the year, volatiles, such as water and C02 seem to migrate towards the equator, which is largley in shadow at high obliquity. Exactly how quickly the polar ice deposits collapse and migrate is still not well constrained. This makes for a nice backdrop to gaming, though, if you want your world to be suffering from sudden droughts and floods in unpredictable ways. * Just a reminder: seasons are a function of a planet's obliquity. At present, the northern hemisphere of Earth is actually closer to the sun during winter than during summer. It's just angled at such a way that the sun is lower in the sky, producing less intense radiation on the surface (in Watts/square meter) which produces the cold season. At 0 obliquity, "seasons" would be driven by eccentricity (the degree of circularity of the planet's orbit). Although there are eccentricity effects on climate (on Earth and Mars), seasonal variation is dominated by obliquity. [/QUOTE]

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