I hope Tom Hall sees that analysis.
Only question I have is re: water levels: Europa is assumed to be largely water. I know it's a moon, Jupiter's gravity is keeping it warm and the whole thing may well be something from further out in the solar system which has ventured in and been trapped by Jupiter's gravity, but how is that explained by those estimations?
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Keening_Product
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Right. So planetary formation has several stages.
Firstly a cloud of gas and dust collapses. a central star(s) forms and begins to shine. At this point the matter in the disk begins to collide and form 'lumps' At this point the cloud begins to differentiate. Close in there is iron and silicates, further out ices as well as 'rocks'.
The lumps will start to concatenate into planetoids. Close planets will be composed of iron and rock while those at about Jupiter's distance will be mainly ices, like Europa, with a smaller rocky core.
If a planet breaches the 'magic limit' of about 2 earth masses or rock and ice it can start sucking in gas and become a gas giant (IF the gas hasn't been blown away by the star.)
So we have rocky planets up close with no water and icy planets further out. This explains Europa.
But then the Jupiter planets start bossing things around. They can whizz right up to their star (See, 'hot jupiters': http://en.wikipedia.org/wiki/Hot_Jupiter ) knocking anything else out of their way like you would swat a mosquito. This sends a bajillion icy comets into the inner star system, watering the rocky planets.
When everything calms down (maybe a billion years after the star started forming) you have some wet rocky inner planets that immediately start losing their water (See Mars and its watery past.) while the outer planets are too cold to change much at all. (However all the watery moons ARE erupting water all over... http://www.nasa.gov/content/goddard/hub ... ter-vapor/ )
So that's how it works. Might be interesting to see Keen on Io.
Firstly a cloud of gas and dust collapses. a central star(s) forms and begins to shine. At this point the matter in the disk begins to collide and form 'lumps' At this point the cloud begins to differentiate. Close in there is iron and silicates, further out ices as well as 'rocks'.
The lumps will start to concatenate into planetoids. Close planets will be composed of iron and rock while those at about Jupiter's distance will be mainly ices, like Europa, with a smaller rocky core.
If a planet breaches the 'magic limit' of about 2 earth masses or rock and ice it can start sucking in gas and become a gas giant (IF the gas hasn't been blown away by the star.)
So we have rocky planets up close with no water and icy planets further out. This explains Europa.
But then the Jupiter planets start bossing things around. They can whizz right up to their star (See, 'hot jupiters': http://en.wikipedia.org/wiki/Hot_Jupiter ) knocking anything else out of their way like you would swat a mosquito. This sends a bajillion icy comets into the inner star system, watering the rocky planets.
When everything calms down (maybe a billion years after the star started forming) you have some wet rocky inner planets that immediately start losing their water (See Mars and its watery past.) while the outer planets are too cold to change much at all. (However all the watery moons ARE erupting water all over... http://www.nasa.gov/content/goddard/hub ... ter-vapor/ )
So that's how it works. Might be interesting to see Keen on Io.
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Keening_Product
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