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Mon 7 Feb, 2005 02:57 pm
A very advanced race could likely assemble a planet with only water with a radius of 4000 miles = same size as Earth. It would have a very thin water vapor atmosphere assuming an average surface temperature of 56 degrees f. It would have less than 1/2 the mass of Earth, so the surface gravity would be about 1/2 that of Earth's surface. The surface temperature could be the result of formation, in which case it would be cooling. Cosmic radiation might be a million times less than in Earth's upper atmosphere, so only a few pounds of water vapor would be disassociated per day. As little as one pound per year of hydrogen lost to space per year. Some hydrogen recombines with free oxygen and perhaps a pound hydrogen would be swept up annually even in the great voids between the galaxies. If there was a sun like ours, 92 million mile away, Hydrogen would be lost in a million years, resulting in an oxygen atmosphere which could hold more water vapor than vacuum, I think. Because of the low gravity, small amounts of oxygen and water vapor would also be lost to space, but the planet would likely last a billion years.
More practical, they would likely start with a planet, like Mercury, but bigger and with scarcely any volatiles, and add a thin veneer of water. This would give a surface gravity about the same as Earth with a thin water vapor atmosphere. Hydrogen loss would be perhaps 100 times less than for the 1/2 gravity water planet. Oxygen and water vapor loss would be negligible, unless radiation was much more intense than we get. A probable magnetic field would also reduce atmosphere loss at least slightly. A water only planet probably cannot have a magnetic field.
A water only planet with 12 times the mass of Earth would have about three times the radius and perhaps 1.5 times the surface gravity of Earth and would loose negligible atmosphere to space even in a some what stronger radiation than we get from our sun. At the core of a water only world, high density water would form, but I think all these have a density less than 4 times that of normal water. Please embellish, refute and/or comment. Neil
In the first instance, with 1/2 earth gravity, I would assume atmospheric pressure to be considerably lower than our norm. You may need to crank in higher moisture content in the atmosphere and more rapid evaporation.
What sort of weather and ocean (planitary) currents are you anticipating? Possibly none, with surface temperature resulting from formation, only?
We'll need some shark people, pirates, and a girl wih a map on her back, showing where land is, but what the pirates don't know is that the map actually designates another planet, but by the time they figure that out they've sacrificed a disgusting ammount (loved ones, money, purified water, etc...).
Quote: A water only planet probably cannot have a magnetic field.
water is composed of oxygen and hydrogen molecules which have charge, therefore I believe they may act as the sources to electric or magnetic fields, as well as be affected by them. however, I think that the polar molecules would arrange themselves in directions which would result in no net charge from the planet so there would not be poles like on Earth.
Why would they do that? Our poles are just water, and they're still polish... um... poley.
Now that I think of it, wouldn't a planet of just water end up as a planet of just ice very quickly? Without a molten core, or closer proximity to the sun.
Hi roger: I think you are correct: No water circulation unless the planet has a large moon or a high mass primary that it circles. Rotation of the water planet would also enhance circulation of water and water vapor.
Life as we know it requires sunlight and carbon dioxide and water or oxygen, food and water. Some micro-organisms use sulphur dioxide, hydrogen sulphide, hydrogen instead of oxygen. All need water and a long list of trace elements. There may be other possibilities, but only water seems unlikely. Neil
But what stops it from freezing?
Yes the water would be frozen once it is in space. there are a lot of planets/moons that are like this already (or largely so) I think, althogh I'm not much into astronomy...I think for example Europa is largely ice
SCoats and stuh are correct. The surface water would cool to 4 degrees c (waters maximum density) and sink to the center. Surface ice might be rare for the first million years until nearly all the water cooled to 4 degrees c. Then there would soon be a thick layer of ice at about minus 270 degrees c on the surface, insulating the 4 degree c water from further cooling except over a very long time. Neil
how would it maintain its shape, without some sort of core, or moon......would it have an atmosphere then too?
oh yes one more thing, where would you get the massive amounts of water to make this planet, even if there was a race that could do this, they would have to destroy a stable planet, just to build a new planet, which would not make any sense.
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