It all started more than five billion years ago. In one of the arms of a great spiral galaxy that came to be known as the Milky Way, about two thirds of the way out from the center, a few scattered atoms and molecules began to congregate. Gases were formed. Microscopic bits of intersteller dust wandered into the mix. Forces of mutual attraction - the beginnings of gravity - began to work, drawing more and more material together.

It took a very long time, but eventually a huge cloud of gas and dust was formed. When it got to be many billions of miles across, it began to take on a life of its own, heating up, and rotating. An intense gravity well formed at the center of this cloud that pulled everything inwards. The more material pulled into the center of the cloud, the denser it became, and the more gravity and heat was produced, until finally the density and the heat became extreme enough to finally ignite, and a star - our Sun - was born.

99.8 % of the cloud was consumed in the birth of the Sun. The 0.2% that was left over became everything else in the solar system, including all the planets and their moons, and all the thousands of asteroids and comets, and anything else trapped in orbit around the Sun, including you and me.

The photo composite above shows all eight planets and their moons in their proper order from the Sun, and accurately shows their sizes, relative to each other and to the Sun. You can easily see how the huge mass of the sun contains 99.8 % of all the matter in our solar system, and how small and frail our little blue/white home is. But although the above picture is scientifically to scale as far as size goes, distance is another matter entirely. The fact is our solar system is really quite an empty place.

If the Sun was only one inch (2.54cm) in diameter, Earth would be the size of a small grain of sand almost 10 feet (3 meters) away. Giant Jupiter would be a large grain of sand almost 50 feet (16 meters) away. Uranus would be a medium sized grain of sand 170 feet (57 meters) away! And believe it or not, poor little I-was-once-a-planet Pluto would be only the size of grain of salt way out at 350 feet (118 meters) away from our little one inch Sun! That our technology can detect such a small object so far away is a bit of a miracle all by itself.

The diagram below accurately shows the relative distances of all the planets from the Sun, and from each other. For size to be to scale as well, you would have to reduce the Sun to a speck of dust, and all the planets to microscopic pin-pricks. The solar system is a very big place, and like the Universe itself (as far as we can detect), mostly cold, empty space.

You can see how the four small solid planets of the inner solar system are all clustered tightly around the Sun, while beyond the asteroid belt, the four giant gas planets of the outer solar system are spread very far apart, a very long way from the warmth and light of the Sun.

Beyond the planets lies the Kuiper Belt, a region of icy debris, some of which are large enough to be classified as dwarf planets, including the former planet Pluto.

Beyond the Kuiper Belt, the gravity of the Sun is not strong enough to keep the chunks of ice and rock that reside there in the same plane as the planets, so that they spread out into a sparsely populated sphere of debris, referred to as the Oort Cloud. When a piece of this debris is disturbed by changing gravitational forces inside or outside our Solar System, and it begins to fall toward the Sun, a comet is born.

Below is an Orrery, a real time graphical representation of the relative positions of the planets in our Solar System, showing where all the planets are right now. Although the positions of the planets relative to each other (and the Sun) are accurate, the size and distances of the planets are decidedly not to scale.

ORRERY - Relative Positions of Planets

(orbits are counter-clockwise)

Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Now, let's take a closer look at this solar system of ours, starting with the maestro, the heart and soul of the solar system, a star called Sol.

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