The Sun contains 99.85% of all the matter in the Solar System. The planets, which condensed out of the same disk of material that formed the Sun, contain only 0.135% of the mass of the solar system. Jupiter contains more than twice the matter of all the other planets combined. Satellites of the planets, comets, asteroids, meteoroids, and the interplanetary medium constitute the remaining 0.015%. Here is a list of the biggest things in the solar system.

Nearly all the solar system by volume appears to be an empty void. This vacuum of "space" actually is made up of the interplanetary medium. This includes various forms of energy and at least two material components: interplanetary dust and interplanetary gas. Interplanetary dust consists of microscopic solid particles. Interplanetary gas is a tenuous flow of gas and charged particles, mostly protons and electrons -- plasma -- which stream from the Sun, called the solar wind.

The solar wind can affect the motion of spacecraft and it has a large effect on comet tails. The speed of the solar wind is about 400 kilometres (250 miles) per second in the vicinity of Earth's orbit. The point at which the solar wind meets the interstellar medium, which is the "solar" wind from other stars, is called the heliopause. It is a boundary theorised to be roughly circular or teardrop-shaped, marking the edge of the Sun's influence perhaps 100 AU from the Sun. The space within the boundary of the heliopause, containing the Sun and solar system, is referred to as the heliosphere.

The solar magnetic field extends outward into interplanetary space; it can be measured on Earth and by spacecraft. The solar magnetic field is the dominating magnetic field throughout the interplanetary regions of the solar system, except in the immediate environment of planets which have their own magnetic fields.

The Terrestrial Planets (Inner Planets)

The terrestrial planets are the four innermost planets in the solar system, Mercury, Venus, Earth and Mars. They are called terrestrial because they have a compact, rocky surface like the Earth's. The planets, Venus, Earth, and Mars have significant atmospheres while Mercury has almost none.

The Jovian Planets (Outer Planets)

Jupiter, Saturn, Uranus, and Neptune are known as the Jovian (Jupiter-like) planets. The Jovian planets are also referred to as the gas giants, although some or all of them might have small solid cores.

Finally there is pluto.htm who classification as a planet is debatable (but accepted by the IAU).

The Origin of the Solar System (Cosmogony)

A cloud of interstellar gas and/or dust (the "solar nebula") was disturbed and collapsed under its own gravity. The disturbance could have been, for example, the shock wave from a nearby supernova.

As the cloud collapsed, it heated up and compressed in the center. The heat was enough to vaporize the dust. This initial collapse should have taken less than 100,000 years.

The center compressed enough to become a protostar and the rest of the gas orbited/flowed around it. Most of that gas flowed inward and added to the mass of the forming star, but the gas continued to rotate. The centrifugal force from that prevented some of the gas from reaching the forming star. Instead, it formed an "accretion disk" around the star. The disk radiated away its energy and cooled off.

Then the gas orbiting the star/protostar may have been unstable and started to compress under its own gravity. This could have produced a double star. It didn’t and instead, the gas cooled off enough for the metal, rock and (far enough from the forming star) ice to condense out into tiny particles. (i.e. some of the gas turned back into dust). The metals condensed almost as soon as the accretion disk formed (4.55-4.56 billion years ago according to isotope measurements of certain meteors); the rock condensed a bit later (between 4.4 and 4.55 billion years ago).

The dust particles collided with each other and formed into larger particles. This went on until the particles got to the size of boulders or small asteroids. Once the larger of these particles got big enough to have nontrivial gravity, their growth accelerated. Their gravity (even if it's very small) gave them an edge over smaller particles; pulling in more, smaller particles, and very quickly, the large objects had accumulated all of the solid matter close to their own orbit. How big they got depends on their distance from the star and the density and composition of the protoplanetary nebula.

In the solar system, the theories say that this is large asteroid to lunar size in the inner solar system, and one to fifteen times the Earth's size in the outer solar system. There would have been a big jump in size somewhere between the current orbits of Mars and Jupiter: the energy from the Sun would have kept ice a vapour at closer distances, so the solid, accretable matter would become much more common beyond a critical distance from the Sun. The accretion of these "planetesimals" is believed to take a few hundred thousand to about twenty million years, with the outermost taking the longest to form.

How big were those protoplanets and how quickly did they form? At about this time, about 1 million years after the nebula cooled, the star would generate a very strong solar wind, which would sweep away all of the gas left in the protoplanetary nebula. If a protoplanet was large enough, its gravity would pull in the nebular gas, and it would become a gas giant. If not, it would remain a rocky or icy body.

At this point, the solar system was composed only of solid, protoplanetary bodies and gas giants. The "planetesimals" slowly collided with each other and became more massive.

Eventually, after ten to a hundred million years, there are ten or so planets, in stable orbits. These planets and their surfaces may be heavily modified by the last, big collision they experience (e.g. the largely metal composition of Mercury or the Moon).

This was the theory of planetary formation as it stood before the discovery of extrasolar planets. The discoveries don't match what the theory predicted. That could be an observational bias (odd solar systems may be easier to detect from Earth) or problems with the theory (probably with subtle points, not the basic outline.)

This is an image of the probable site of planet formation around a star known as HR 4796, about 220 light-years from Earth in the constellation Centaurus. The image, taken with an infrared camera, shows a swirling disc of dust around the star. Within the disc is a telltale empty region that may have been swept clean when material was pulled into newly formed planetary bodies. This may be what our solar system looked like at the end of its main planetary formation phase. Comets may be forming in the disc's outer portion from remaining debris.

The apparent diameter of the dust disc around HR 4796 is about 200 astronomical units. The diameter of the cleared inner region is about 100 astronomical units, slightly larger than our own solar system.