Is jupiter really that big?

[griffithsuk]

Just a guess really jupiter really does stand out compared to the others, what happened in history to get that big?

 

Another theory of mine, matter from the planets came from the sun. matter collects together close to the sun producing a new planet. and pushes the other older planets outwards.

 

I think theres a lot of history here.Like rings in grain of wood we have different matter from the sun at different times of it's life producing different planets maybe?

 

If were traveling to mars for whichever reasons, thats related to the past. Venus will be the future.

Edited May 12, 2011 by griffithsuk

[Schrödinger's hat]

Umm, the current scientific theory is that the planets and the sun formed at about the same time.

The idea is that there was a big cloud of dust and gas from a previous star exploding (it needs to be a supernova remnant for there to be metal in it, otherwise only a star and maybe a gas giant would be formed).

 

The whole cloud is shrinking because of gravity and the cloud would have tiny imperfections in it, some bits are denser than others.

 

What happens is the gravity from these dense bits pulls a tiny bit stronger than the gravity from the less dense bits, so more dust gathers there.

Slowly they build up, and some of them merge together.

The biggest one will eventually be a star, if there's another big one near it they tend to merge together and form one even bigger one.

Eventually gravity pulls the gas together and it gets hotter and hotter, the star ignites.

As this is happening the clumps close to the star can't hold on to the gas around them, the light and energy from the star, along with the heat from the condensing cloud push most of the gas away so that all that is left is the heavy stuff that sank to the middle and a thin atmosphere.

 

Further out it's cooler and easier to hold on to light hydrogen, oxygen, nitrogen etc. so you get big gassy planets.

Also if planets are big enough they can hold onto the gas better.

 

I'm glossing over a whole lot of stuff about the role electrostatic attraction plays in the early stages, and theories on formation of hot Jupiters in other solar systems, but this is reasonably close to the current model.

[griffithsuk]

(it needs to be a supernova remnant for there to be metal in it, otherwise only a star and maybe a gas giant would be formed).

 

 

Interesting stuff.

 

If it was from a previous star, them im guessing the mixture was the same throughout, why do the planets look so different?

Edited May 12, 2011 by griffithsuk

[Schrödinger's hat]

Well, the inner planets are mostly rocky because most of the gas got pushed away or escaped on its own.

Depending on how big they were they cooled down and solidified at different rates.

Mercury was tiny and couldn't hold on to much stuff at all, so it's mostly iron and other heavy stuff.

Venus and earth were bigger, the surface constantly gets recycled by volcanism or plate tectonics, different thickness of atmosphere is the other major difference.

Mars would be similar except that it was a bit smaller so it cooled down and solidified, the stuff on the surface has been there for a long time so the iron all reacted with oxygen, compare it to really old land on earth like central Australia or US. Also life on earth came and changed everything.

Jupiter has lots of everything because it was one of the bigger clumps to begin with, but not big and close enough to either merge with the sun, or become a star itself. This sort of gave it a head start and allowed it to gobble up more of the available stuff faster than the other planets. Most of the stuff in the cloud was hydrogen and helium, so that's what it is composed of. (it has a fairly large core of metals as well).

Saturn is similar, but it was originally smaller, so it's much less massive.

It was, on the other hand, a bit further out so it got to hold on to more gas for its size.

As a result it is less dense than Jupiter.

It's a similar temperature and composition to Jupiter so it looks the same.

 

Further out it's colder, so it's much easier to hold on to nitrogen/oxygen etc. so the outer planets/dwarf planets tend to be made out of ice and various other frozen compounds of hydrogen nitrogen, oxygen, hydrogen and carbon.

Hydrogen and helium are pretty hard to hold on to so you get things like the dwarf planets and various moons of all the gas giants.

I don't know the exact composition of Uranus/Neptune compared to Saturn/Jupiter, but I believe there is a higher proportion of oxygen/nitrogen in their atmosphere making them blue-er because of the lower temp.

All in all it's a very complicated process and temperatures and sizes of planets at different times during their formation, along with what they hit and interacted with has a huge effect on composition.

[PerpetuallyConfused]

Consider the milky way galaxy as a kind of model for early space dust. You have the centre of the galaxy/the sun rotating the fastest, with the largest mass, pulling the rest of the accretion disk around at a non-constant angular velocity compared to distance. So, the closer you are, the faster you will spin around the centre, approaching the speed of the central object (supermassive black hole / the sun).

 

Now this may explain the discrepancy between some of the materials discovered within our solar system. As well as raw temperature, which the hat explained in the last post, we also have angular velocity and momentum to account for.

 

I also often see Jupiter described as a 'failed star' with simply not enough mass to start its nuclear fusion. This makes complete sense as, there are more solar systems in our galaxy that have more than one star, than singular systems. Conceptually, this could be caused by an unbalanced distribution of mass and particles within the stellar cloud.

 

Imagine, for example, that a star explodes. this creates a roughly spherical shape to the matter distribution resulting from the explosion. Now imagine a rogue planet wandering through the field, aeons before it had begun to reform into a star, and creating a massive distortion in the shape of the field. This could lead to the unbalanced distribution as described, which could in turn lead to pockets of higher mass, which could lead to more than 1 star forming from the same stellar dust field. Or, as in this case, could create a relatively large planet.

[Ophiolite]

Perpetually, I am not sure where to begin with your enthusiastic, but inaccurate post.

1. The galaxy is not a good model for 'space dust'.

2. The sun formed primarily from gas, not dust.

3. The sun doesn't 'pull' the the accretion disk around with it.

4. The bulk of the angular momentum in the solar system resides in the planets not in the sun.

5. You have not provided any mechanism wherein the differences in velocity and momentum could produce the range in planetary compositions.

6. Giant molecular clouds, the breeding grounds of stars, are not circular in shape and do not arise from a single supernova.

7. Rogue planets do not reform into stars.

 

Please accept that I am seeking to correct errors in your thinking, not attacking you.

 

And welcome to the forum.