Ok, supposedly Jupiter was supposed to be a star but never quite made it. Could it ever be a planet with life on it, like ours? Or is it too big? Can a planet ever be to small to have life on it?

Ok, supposedly Jupiter was supposed to be a star but never quite made it. Could it ever be a planet with life on it, like ours? Or is it too big? Can a planet ever be to small to have life on it?

Jupiter is a gassy planet, no surface ;)

do all large planets of that size, not have a surface? So life couldn't start on them could it.

do all large planets of that size, not have a surface? So life couldn't start on them could it.

I don't think all Jupiter-sized planets are gassy planets. But all large planets in our solar system are.
- Jupiter
- Neptune
- Saturn
- Uranus

The correct term is Gas giant btw.
http://en.wikipedia.org/wiki/Gas_giant

What you are looking for is this:

"A Super-Earth is the popular misnomer for a large "terrestrial planet" that is also in a planetary system, orbiting a star. The standard criterion is that it has a least twice the mass of Earth, but smaller than Uranus, or up to ten Earth masses. Also, they are usually not lacking in insolation from the parent star(s) as cold planets of that size would in the systems formation lose less gas mass and form into full Gas Giants."
Read more: http://en.wikipedia.org/wiki/Super-earth

Argh!
I don't care what they are called Enmos!!!

I want to know about life sustaining abilities based on size. :p

Argh!
I don't care what they are called Enmos!!!

I want to know about life sustaining abilities based on size. :p

Go with earth-sized planets then.
Reading the articles might give you an idea though.
You mean human life specifically ?

Go with earth-sized planets then.
Reading the articles might give you an idea though.
You mean human life specifically ?

what about smaller than earth size? And no, not human like life, but maybe something a bit bigger than microbes and bacteria.

what about smaller than earth size? And no, not human like life, but maybe something a bit bigger than microbes and bacteria.

I suppose if you are talking about any sort of life form there aren't many limits. Provided there is liquid water available. And even that is only based on our knowledge of earth life.

Isn't the atmospheric pressure on Jupiter too high?

Argh!
I don't care what they are called Enmos!!!

I want to know about life sustaining abilities based on size. :p

Size doesn't matter

If life needs an atmosphere, then size does matter. Depending on the amount of heat received by an atmosphere and the gravity (mass) of the planet, the molecular escape velocity of different types of gasses could allow them to be "blown off" long before life got started.

Gas giants might be capable of supporting life; they have plenty of available energy, and can have quantities of all the elements required for biology-as-we-know-it; carbon, hydrogen, oxygen and nitrogen.

Hwever there are two main problems with gas giant life, in my opinion. Firstly there is no mechanism I can see which would allow the molecules of life to become locally concentrated. On Earth organic chemicals could become concentrated in shallow pools or inside muds and clays, allowing ever more complex compounds to form. It is difficult to imagine how this could occur in a gas giant atmosphere.

Perhaps life could form on a moon of such a gas giant and later infect the giant by transfer of material across the relatively small gap between planet and moon.

Secondly the main component of a gas giant's atmosphere is hydrogen, the lightest gas. This means that a lifeform must be composed almost completely of hydrogen, or it will be heavier than air and it will sink. One imagines a creature with cells full of gas, rather than full of liquid cytoplasm.

Isn't Jupiter supposed to have a rocky core covered with metallic hydrogen?

Deeper down in the atmosphere, things would be much slower and much denser, even noticeably warmer. I don't see why life of some kind might not form there, maybe utilising some of the silicon? While it does have some gaseous elements, a number of these can be liquid at low temperatures or as compounds. Or life near the core boundary might exist under huge pressures (as in the bottoms of our oceans) so might that not hold them in a form that could also survive the high temperatures there?

The problem with talking about life elsewhere is that we automatically think : "Would anything living on Earth be able to survive there?" when there could be something totally unknown to us living there.

As to smallest size, it would need the ingredients to produce life but may survive with almost no atmosphere, able to survive casual bombardment of radiation from space. But such life would probably never be larger than litchen, though some kind of hive mind might be possible producing a fair degree of intelligence, were there enough to stimulate it's evolution. Life underground would also be a possibility.

Orleander:

do all large planets of that size, not have a surface? So life couldn't start on them could it.

Jupiter may have a surface, buried deep down under its layers of clouds. However, if it does then the pressure and gravity at the surface would be enormous. And the kinds of chemical elements we normally associate with life are unlikely to exist at that surface.

Ok, supposedly Jupiter was supposed to be a star but never quite made it. Could it ever be a planet with life on it, like ours? Or is it too big? Can a planet ever be to small to have life on it?

Some have suggested that Jupiter might have life in its atmosphere, again a fair way down in the clouds or else we would have detected it by now.

A planet can be too small to have life on it. If a planet is too small, its gravity can be too low to hold onto gases like oxygen and nitrogen. Our Earth can't hold onto hydrogen and helium as it is, which is one reason why Jupiter has lots of hydrogen and helium while Earth doesn't have much. The planet Mars, from memory, can't hold onto oxygen indefinitely, although when it was formed it may have had some heavier gases in its atmosphere.

Once you get to the size of our Moon, no gases are held, which explains why the Moon has no atmosphere at all.

If life needs an atmosphere, then size does matter. Depending on the amount of heat received by an atmosphere and the gravity (mass) of the planet, the molecular escape velocity of different types of gasses could allow them to be "blown off" long before life got started.

I had something different in mind

I had something different in mind

what?


and thanks guys! I appreciate the answers!

what?


and thanks guys! I appreciate the answers!

That would be telling.

I seem to remember that the atmospheric pressure on the centre of Jupiter is about 7 tons per square inch whereas on earth it is 15 pounds.

Isn't Jupiter supposed to have a rocky core covered with metallic hydrogen?

Deeper down in the atmosphere, things would be much slower and much denser, even noticeably warmer. I don't see why life of some kind might not form there, maybe utilising some of the silicon? While it does have some gaseous elements, a number of these can be liquid at low temperatures or as compounds. Or life near the core boundary might exist under huge pressures (as in the bottoms of our oceans) so might that not hold them in a form that could also survive the high temperatures there?



At those depths Jupiter is so hot that ordinary chemistry can't work, so 'life-as-we-know-it' couldn't exist. If some sort of organisation could develop in the metallic hydrogen layer then that would be certainly life as we don't know it.