nine planets The Nine Planets, the Eight Planets

A Multimedia Tour of the Solar System:

one star, eight planets, and more

by Bill Arnett

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The New Solar System

Summarizes what we've learned from interplanetary explorations in the last 25 years. My primary reference for The Nine Planets.

T. Rex and the Crater of Doom

The story of the discovery of the impact crater that doomed the dinosaurs. Nice description of how science works in the real world.

Encyclopedia of the Solar System

A more scholarly introduction to planetary science for those who want to dig a little deeper.

The Compact NASA Atlas of the Solar System

This 'road map' of the solar system contains lots of maps and data as well as photos.

Bad Astronomy

The truth is out there; so is a lot of baloney. Here's the straight story on many popular urban legends, myths and misconceptions. Great fun, too!

Build Your Own Telescope

Want to see the planets for yourself? It's actually pretty easy to make a simple but powerful telescope. Here's how.

This website is an overview of the history, mythology, and current scientific knowledge of the planets, moons and other objects in our solar system. Each page has my text and NASA's images, some have sounds and movies, most provide references to additional related information.

All eight planets can be seen with a small telescope; or binoculars. And large observatories continue to provide much useful information. But the possibility of getting up close with interplanetary spacecraft has revolutionized planetary science. Very little of this site would have been possible without the space program.

Nevertheless, there's a lot that you can see with very modest equipment or even with just your own eyes. Past generations of people found beauty and a sense of wonder contemplating the night sky. Today's scientific knowledge further enhances and deepens that experience. And you can share in it by simply going out in the evening and looking up.

The IAU has changed the definition of "planet" so that Pluto no longer qualifies. There are now officially only eight planets in our solar system. Of course this change in terminology does not affect what's actually out there. In the end, it's not very important how we classify the various objects in our solar system. What is important is to learn about their physical nature and their histories.

The most recent version of this site can be found at

Our knowledge of our solar system is extensive. But it is far from complete. Some of the worlds have never even been photographed up close. The Nine Planets is an overview of what we know today. We are still exploring. Much more is still to come:

We shall not cease from exploration, and the end of all our exploring will be to arrive where we started and know the place for the first time.
-- T. S. Eliot

nine planets ... Intro/FAQ ... Overview ... Sun ... Data
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Copyright © 1994-2006 by William A. Arnett; last updated: 2006 Aug 25
The most recent version of this site can be found at