What's the ultimate size for a terrestrial plant

Since lately there has been many discovery's of giant gasplanets around other stars. I was wondering how big can a terrestrial-type planet get?
And what happens to such a planet when it gets to big ?
Any ideas here on this subject?

 

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Ive heard that when a terrestrial planet gets to big it become a water world with oceans that could be hundreds of km deep. It will also be a very active world with planet wide volcanic activity.

 

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You're limited by the amount of heavy elements a circumstellar nebula can contain. Since the interstellar medium - and denser nebulae - are over 90% hydrogen and helium, any rocky accretion mass must (probably) occur close enough to a protostar for those light elements to be driven away first. Otherwise, the big planetary embryos will inevitable draw in a huge envelope of hydrogen and helium, thus becoming gas giants.

A protostar a few times heavier than the Sun might well have more rocky material in its inner disc, and a broader zone of hydrogen blow-off. Still, since most of the mass of the disc will have been hydrogen, it's unlikely that enough heavy elements could accumulate to form a planet of more than 20 or 30 Earth masses. And it would be likely to form several smaller planets than a single huge one.

That said, a super-Earth with a few times our planet's mass would be impressive indeed. As Wellborn said, it might well be entirely oceanic, but with such powerful volcanism that its ocean floor was never stable. Costant turmoil and superheated, compressed water in the depths would drive gigantic surface whirlpools, waterspouts, and superstorms.

If there was any dry land on the planet, the high surface gravity would result in relatively flattened topography. Mountain ranges would form in low relief and be quickly eroded. Any living things would have to be short and stocky to support themselves. All animals might spend their lives flat against the ground, crawling like slugs or millipedes.

Then again, it might be that any terrestrial world more than a couple of Earth masses would have a dense, greenhouse atmosphere, inevitably leading to runaway warming and Venus-type surface conditions.

Does anyone have an imaginative painting of a giant terrestrial planet?

 

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Yes as a planet get bigger you have the worry about the atmosphere, its thickness will increase global warming and cut down on light toe the surface. Earth its self had most of its atmosphere blasted away in a collision so powerful that it created our moon from debris. If we did not suffer the collision it likely we would have ended up like Venus with a atmosphere many times thicker then our present one. So to make the planet bigger you need to cut down on the amount of volatiles by some way, say a solar system much shorter on volatiles then our own, or a planet much more hammered then our own.

Also you have to worry about what kind of sun it has, as bigger blue class stars only last a few million years. You want yellow or red stars.

 

Wasn't there also a theory about a world entirely composed of water? But it would have to be between a certain size range, or else it would mess up. I suppose this would be possible, but you would probably have to start with foreign bacteria being introduced, and would have to already have other organic chemicals in the water. But as of now, thats just theory. :m:

 

You'll be limited to the stability of the atomic nucleus, in the end, because if a gas giant becomes too big, whoosh. It ignites

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>> when a terrestrial planet gets to big it become a water world

joke huh ?

funny how water is postulated to be everywhere and yet not one drop has been verified....

 

This is one of my worlds, based on a real simulation by Sean Raymond; it is 3.85 the mass of Earth, and has an ocean 75km deep covering a dense ice mantle. The gravity is 1.5 gee; primitive life is present
(for the benefit of Zarkov)

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While this one, a smaller terrestrial, is much larger than Earth; it too would have been a waterworld but it lost most of its volatiles in a late collision with a major planetesimal;

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(the ring is artificial)

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SF worldbuilding at
www.orionsarm.com

 

But you would be very unlikely to get a world entirely of water; even if you melted one of the icy moons of Saturn or Neptune you would end up with a substantial rocky core at the centre.

 

The giant planets Uranus and Neptune may be composed mainly of water, with a rocky core of 1 or 2 Earth masses. If such an "ice giant" were to spiral in closer to its sun - like the hot Jupiters discovered over the last decade seem to have done - the increased temperature would strip away its outer atmosphere of primaeval gases and leave a visible water surface. The remaining atmosphere might even become fairly Earthlike. Such waterworlds may be just as common as hot Jupiters, and detectable within a few years.

http://www.sciscoop.com/story/2004/2/12/7265/74952

 

Oh yes- here is one of those as well, but without the water;

this world started out as a gas giant on the edge of its solar system, but spiraled inwards to become a chthonian world, after losing all its volatiles...
gravity 2g, mass 10x earths, temp 1700 c

I expect I will have to try my hand at a 'melted ice core' world next

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"Try your hand?" So you generate those graphics yourself, Eburacum?

Is it pure artistry, or some sort of planet simulator package which comes up with a picture based on parameters you input? If the latter, please tell me where I can get the software!

 

The limit for a terrestrial plant seems to be around the hight of the giant sequoia, and the reason has to do with the hight of the water column that can be supported by capillary action. Any higher, and the upper limbs could not get enough water. Planets with different gravity might support higher plants.

 

Yes; it is Celestia; I am still learning all the tricks, but my pictures are getting better (I believe).
Many people use Celestia to model the Solar System and the asteroids, moons and satellites that exist in the real world; others (like me) make textures in simple Paint programs for imaginary worlds around some of the hundred thousand real stars in the progam.
Here are a couple more-

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An earthlike ocean world

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A dying wet-greenhouse world

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An earth-like world orbiting Gamma Cephei b

----------------
SF worldbuilding at
www.orionsarm.com

 

LOL

 

Thanks for the link, Eburacum.

You dying wet-greenhouse world, Oshiq: is that meant to resemble Earth a billion years or so hence? I like the green valleys surrounded by desert. Perhaps the final flowering of life on Oshiq would be a planetwide Egypt-type culture, based on annual floods and worship of the rivers.

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Download Celestia today for free! http://www.shatters.net/celestia/

 

ya and there is a fungus in ireland that is over 50miles wide!