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 Question about a hypothetical planet

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Apollo

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PostSubject: Question about a hypothetical planet    Tue Aug 23, 2011 12:52 pm

Hello. Sorry that my first post is made in order to "steal" some knowledge but I need to know what conditions might be needed in order for such a planet to exist:

1. The year is 437 days. In order to still have life (and temperatures) as we have on earth, does the sun have to be bigger I assume? If it's bigger, can there be other complications?
2. The north to be quite hot (60C and above) and the south very cold (-50C and below). The north doesn't necessarily has to be also the pole, could be the whole or most of the north hemisphere. Can this be achieved by having the north pole perpendicular on the sun?
3. No seasons in the area between the hot north and the cold south and if possible that day and night duration to be roughly the same or at least constant. There will be a big ocean (roughly 70% of the area of the planet, less if it helps the north stay hot Smile )

Thank you!
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andy 'astrojunkie'
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PostSubject: Re: Question about a hypothetical planet    Tue Aug 23, 2011 12:58 pm

wow...possibly lol usually when scientists say no, its impossible for this to happen it happens lol, I cant say for sure, i expect someone can though, bit exact lol... Smile

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scopeman

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PostSubject: Re: Question about a hypothetical planet    Tue Aug 23, 2011 1:00 pm

Apollo wrote:
Hello. Sorry that my first post is made in order to "steal" some knowledge but I need to know what conditions might be needed in order for such a planet to exist:

1. The year is 437 days. In order to still have life (and temperatures) as we have on earth, does the sun have to be bigger I assume? If it's bigger, can there be other complications?

Either that or the atmosphere has to be substantially richer in greenhouse gasses (437 days is, as memory serves, less than the Martian year and Mars is thought to have once had liquid water conditions). An atmosphere with the necessary CO2 (the most likely primary greenhouse gas) would probably be toxic to humans, although I haven't done the math (CO2 is logarithmic with temperature with, as I remember, every doubling raising the temperate 3 C). A much more potent trace greenhouse gas is a possibility if human habitability is desired, generating such naturally I leave as an exercise to you (I have no idea how it would happen, though I imagine some kind of biosynthesis and biological feedback cycle is by far the most likely pathway).

Quote :
2. The north to be quite hot (60C and above) and the south very cold (-50C and below). The north doesn't necessarily has to be also the pole, could be the whole or most of the north hemisphere. Can this be achieved by having the north pole perpendicular on the sun?

A bigger sun will have a somewhat different spectrum of light, as I remember more UV. However, this might actually translate to less UV at the surface, surprisingly enough - UV at the surface is determined by the balance between ozone-creating and ozone-destroying reactions in the atmosphere and doesn't scale neatly with UV at the top of the atmosphere.

Quote :
3. No seasons in the area between the hot north and the cold south and if possible that day and night duration to be roughly the same or at least constant. There will be a big ocean (roughly 70% of the area of the planet, less if it helps the north stay hot Smile )



Thank you!

This would be difficult as described. A Uranus-like arrangement (~90 degree axis tilt) would generate extreme seasonal differences, but the hot/light and cold/dark hemispheres would switch every year. It sounds like maybe what you want is a world tidelocked to the star, like our moon is tidelocked to Earth. If you don't want the cold hemisphere to be perpetually dark perhaps this could be a binary star system, with a companion giving enough light to generate daylight on the cold hemisphere but not enough to warm it significantly.

Hope this helps. I can try to dig up some references if desired.
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Apollo

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PostSubject: Re: Question about a hypothetical planet    Tue Aug 23, 2011 1:03 pm

Thank you for the answer.

The north hemisphere or pole doesn't necessarily has to be dark just cold but cold at all times. And I need no seasons in the middle area, either temperate or sub-tropical climate. The middle area doesn't have to be around the equator, could be more south. Or at least something like: south pole very cold then an area with a permanent nice climate then a hot area and then whatever, could be that the whole north is hot or just a wide zone around the planet and after it again a normal area.
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Clive_D



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PostSubject: Re: Question about a hypothetical planet    Tue Aug 23, 2011 1:05 pm

Earth's Antarctic zone is cooler than Earth's Arctic zone in spite of Earth being farthest from the Sun on January 5th each year. I don't think there is scarcely any temperature difference between the Tropic of Cancer and the Tropic of Capricorn = very little temperature change in the tropic regions of Earth.
If your planet's orbit is highly elliptic. It will be hotter when closer to the Sun, during half of the year, but that effect could be split equally between the Northern and Southern Hemispheres. The tilt of the axis of rotation favors the the northern hemisphere or the Southern hemisphere during half of the year.
437 days instead of 365.24 days will only make the Winters slightly colder and the Summers slightly warmer. Assuming the climate change people are on the right track, we don't want a bigger, or hotter Sun.
Pole perpendicular to the Sun = 90 degrees tilt occurs briefly at 1/2 year intervals, so I don't think that will help your problem, but close to zero tilt of the axis may be helpful. Zero tilt also means the days are always slightly longer than the nights, and only the poles will be cold, except when the planet is farthest from the sun and for a few weeks following. Earth is tilted about 23 degrees.
You can possibly achieve a 50 degree c colder average temperature at the South pole, compared to the North pole, by having a large, high above sealevel continent centered on the South pole and only small low islands near the North pole. A 110 degrees c difference would occur only very rarely unless the equatorial region also has wide temperature differences, I think.
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