In our solar system;why are the outer planets bigger and inner planets smaller?

Question

It's a science question I have to do a paragraph on so give me a detailed answer.

Answer 1

That's a good question. The hints here are the three different types of planetary bodies present in the solar system: rocky (mercury, venus, earth and mars), the gas planets (uranus, jupiter and neptune) and the outer Kuiper belt objects. There is no proven answer here, but common sense tells you that as material coalesced into a star to form our sun, matter left over to form the planets was either unevenly distributed or affected by the sun's gravity. It can't be a coincidence that the final three planets are all gas giants. Rocky material was either ejected from the sun as it ignited, or drawn in by its gravity. Dispersed gas didn't feel the gravitational pull as hard.

Answer 2

Actually we can´t really say. Our computer models for how the solarsystem formed cannot even explain Neptune and Uranus. And with solarsystems found each day where Jupiter sized worlds are found to be orbiting its parent star at Mercurys distance we seem to be learning less...
The outer planets have huge rocky cores, Jupiter has one 13 times as massive as earth, and for this reason they have kept all the lighter materials from when the solarsystem was born while the terrestrial planets lost those huge hydrogen and helium envelopes as soon as the sun ignited. But why the massive planets are out there and not nearer to the sun is not really known. We do know that uneven distribution of mass is common elsewhere as binary and multiple starsystems are very common. If Jupiter had been 80 times more massive it would have been a star.

Answer 3

It's not always the case---of the hundred or so other solar systems we know about, most have giant planets close to the star. Of course it's easier to detect big planets close to the star than small planets, so we don't know if it's a general rule.

In some solar systems, the big gas giants (like Jupiter) migrate inwards, taking out the smaller planets closer in as it goes. That did not happen in our solar system.

One hint: if it gets too warm, the gasses that make gas giants can evaporate, leaving only rocks behind.

Answer 4

To be absolutely honest, we don't know - possibly just chance. So far astronomers have found planets around other stars but their equipment is only able to detect large planets close to their stars, and yes, it appears that there are lots of them. So there is no reason why the large planets could not be the close ones and the small ones the distant ones. Remember that Pluto (although no longer officially a planet) is small and on the outskirts of our solar system.

Answer 5

The inner planets are all made of mostly rock. The large outer planets might have a rocky core but they are mostly gas. (hydrogen and helium)
If a gas giant were close to the sun, the heat would evaporate most or all of its gases, then only its small rocky core would remain.

Answer 6

Well for one, the first 3 inner planets are solid, where as (most) the larger outer planets are gases.

Answer 7

Pluto is a DWARF PLANET!!!

It's probably dependant on if it has an internal heating source, how far it is away from the sun... and where the nearby astroid belts are, if it always has asteroids running into it and staying it could multiply by size or decrease by size... But i dont know...

Answer 8

Well, Pluto's not considered a planet any more. It was proven. But I think it has something to do with the gravitational pull of the sun or something like that.

Answer 9

They're not. Pluto is smaller than most of the inner planets.

Answer 10

are they? i thought they were smaller in the inner and outer parts and bigger in the middle? (jupiter,saturn,uranus)