Nine Planets

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 our text and NASA's images, some have sounds and movies, most provide references to additional related information. In association with our friends at Solar System Scope we now have an interactive tour of the solar system (takes a while to load and opens in a new window)

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.

• Introduction and FAQ
• What's New
• Express Tour
• Solar System Overview
• The Sun
  • Mercury
  • Venus
  • Earth
    • The Moon
  • Mars
    • Phobos
    • Deimos
  • Jupiter
    • Metis, Adrastea, Amalthea and Thebe
    • Io
    • Europa
    • Ganymede
    • Callisto
    • Leda, Himalia, Lysithea, Elara, Ananke, Carme, Pasiphae and Sinope
    • Recently discovered moons
  • Saturn
    • Pan and Atlas
    • Prometheus and Pandora
    • Epimetheus
    • Janus
    • Mimas
    • Enceladus
    • Tethys, Telesto and Calypso
    • Dione and Helene
    • Rhea
    • Titan
    • Hyperion
    • Iapetus
    • Phoebe
    • Recently discovered satellites
  • Uranus
    • Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda and Puck
    • Miranda
    • Ariel
    • Umbriel
    • Titania
    • Oberon
    • Caliban, Sycorax, Prospero, Setebos, Stephano, and Trinculo
  • Neptune
    • Naiad, Thalassa, Despina and Galatea
    • Larissa
    • Proteus
    • Triton
    • Nereid
  • Pluto
    • Charon
    • Nix and Hydra
  • Dwarf Planets
    • Pluto
    • Ceres
    • Eris
    • Makemake and Haumea
  • Small Bodies
    • Comets
    • Comet Halley
    • Comet Shoemaker-Levy 9
    • The Kuiper Belt and the Oort Cloud
    • Sedna
    • Asteroids
    • 951 Gaspra
    • 243 Ida
    • 253 Mathilde
    • 433 Eros
    • Meteors, Meteorites and Impacts
    • The Interplanetary Medium
• Other Solar Systems
• Seeing the Solar System with your own eyes (or binoculars or a small telescope)
• Spacecraft involved in planetary science
• How you can help support the continued exploration of space
• Glossary of technical terms and proper names
• Appendices
  • Solar System Data: Orbital, Physical, Misc
  • Extrema, the biggest, brightest, etc.
  • Discovery Chronology
  • The Origin of the Solar System
  • Planetary Linguistics, including the planets' names in various languages
  • Astronomical Names and how they're assigned
  • Hypothetical Planets (Planet X et al, or "Don't believe everything you read")
  • Planetary Picture List: images on the Net; posters, calendars and prints offline
  • Planetary Music: classical music relating to the planets
  • Bibliography and credits for those who helped make this possible
  • Mirror sites
  • Copyright Notice
• Search this site or the whole Web:

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