(Click on planets in the picture to see info about each.)
A Vast, Wonderous Place
Our solar system consists of the sun, 8 planets (perhaps 9), 5 dwarf planets, at least 146 moons and countless asteroids, comets and meteoroids. Stretching from the sun out to the heliopause, the solar system covers a mind-boggling distance of 11 billion miles. As yet, only one manmade object (the Voyager 1 probe) has crossed into the heliopause.
The sun, of course, is at the center of our solar system and contains 99.8% of the solar system's mass. Everything else orbits around the sun in an elliptical orbit. The four inner planets - Mercury, Venus, Earth and Mars - are mainly composed of rock and iron. In between the inner and outer planets is the massive Asteroid Belt , which contains an estimated 750,000+ asteroids as well as the dwarf planet Ceres. The outer planets - Jupiter, Saturn, Uranus and Neptune - have no solid surfaces and are much bigger than the inner planets. While Saturn may be famous for its incredible ring system, in fact all the outer planets have rings.
Beyond the outer planets lies the Kuiper Belt, a gigantic region filled with icy bodies including the Pluto system and lesser known dwarf planets like Makemake and Eris. If there is a 9th planet (and the evidence looks good for that) it would follow an orbit around the sun 600 times farther than that of Earth. Way past the Kuiper Belt is the Oort Cloud, whose distance is anywhere between 8 and 167 times that of the hypothetical 9th planet's orbit. The Oort Cloud is estimated to contain 2 trillion icy bodies. At the farthest reaches of the solar system is the heliosphere. The heliosphere is defined as the region where the sun's solar wind is rapidly slowed to subsonic speeds upon reaching termination shock, which marks the start of interaction with the interstellar medium.
At heliopause, the sun's wind is completely stopped. The temperature of charged particles drops dramatically, the magnetic field changes direction and the prevalence of cosmic rays increases. At this point, our home planet is nothing more than a tiny blip. Beyond that is the Milky Way, of which the solar system comprises only .0032%!
While the info contained in this site might not extend to the edge of the universe, it should help give you an appreciation for how utterly bizarre and beautiful our solar system is as well as, perhaps, inspire you to reach for the stars.
By Aaron Feigenbaum