Help Shape the Future of Space Exploration

Join The Planetary Society Now  arrow.png

Join our eNewsletter for updates & action alerts

    Please leave this field empty
Explore

Compare the Planets

Comparing the physical characteristics of the worlds in our solar system (and beyond)

The worlds of our solar system come in all shapes, sizes, and colors. Red-eyed Jupiter, ringed Saturn, and frigid Uranus and Neptune are giant gassy globes containing nearly all of the matter in the solar system. These Jovian planets, or gas giants, are huge worlds of air, clouds, and fluid that may have no solid surfaces no matter how deep you go. Everything else in the solar system is just rock, ice, and dust. The largest rockballs are known as the terrestrial planets: Mercury, Venus, Earth, and Mars, with our Moon usually considered part of the club, and now Vesta is applying for membership. Earth is the biggest of all the rocky worlds.

But the planets are not the only worlds of the solar system. All but two of the planets are orbited by moons, each of them a world unto itself. The largest moons are bigger than the smallest planets, and 16 or 17 would qualify as dwarf planets if they orbited the Sun. There are more than 100 Kuiper belt dwarf planets, but only one among the asteroids, Ceres.

Six solid worlds -- Venus, Earth, Mars, Titan, Triton, and Pluto -- have atmospheres dense enough to produce weather. Eris likely does, when it is near its perihelion. We have witnessed active geology on four worlds -- Earth, Io, Enceladus, and Triton -- and we suspect it on Venus, Europa, and Titan. Comparing the same processes across many worlds helps us to understand how each planet's unique composition and history influence its present state, and will help us predict what to expect on Earth in the future.

Pretty Pictures with Many Worlds

Saturn with Tethys and Mimas' shadow

Saturn with Tethys and Mimas' shadow

This image shows Saturn with Tethys below the rings and a shadow cast on Saturn's disk by Mimas.

Filed under pretty pictures, Tethys, Cassini, amateur image processing, many worlds, Saturn, Mimas, Saturn's rings

Dione and Friends

Dione and Friends

Black-and-white montage of Cassini images of Saturn's rings and moons. From left to right, they are Mimas, Dione, Epimetheus, and Prometheus. From a series of images taken December 12, 2011.

Filed under Dione, pretty pictures, Cassini, amateur image processing, Saturn's small moons, global views, Saturn's moons, many worlds, Mimas

Dances with Moons

Dances with Moons

Cassini captures "mutual event" movies to refine the precision with which we know the orbits of Saturn's moons. On September 17, 2011, Cassini took four such movies in rapid succession: Tethys with Titan at about 0100 UTC; Rhea with Titan at 0130; Enceladus with Titan at about 1030; and, at the end, at 1200, a movie with Titan, Dione, Saturn's rings, Pandora, and Pan.

Filed under Enceladus, Dione, Cassini, Tethys, Titan, Rhea, Saturn's small moons, global views, Saturn's moons, many worlds, animation, Saturn's rings, pretty pictures, amateur image processing

Items 4 - 6 of 100  Previous12345678910Next

Section Highlights

Planetary Facts

Mass, diameter, density, gravity, orbital characteristics, presented both in metric units and measured relative to Earth.

More »

Asteroids and Comets Visited by Spacecraft

A comparison of all the asteroids and comets ever visited by spacecraft, up to date as of November 10 (when Deep Impact flew past Hartley 2). Vesta is not included.

More »

Every Round Object in the Solar System, to Scale

A correctly scaled, reasonably correctly colored view of the largest bodies in the solar system.

More »

Facebook Twitter Email RSS AddThis

JOIN THE
PLANETARY SOCIETY

Our Curiosity Knows No Bounds!

Become a member of The Planetary Society and together we will create the future of space exploration.

Join Us

Stand Up for Space!

Be a Space Advocate

Sign the petitions to your Representative and Senators urging them to commit NASA to a major scientific mission to Europa and restore the Planetary Science budget to its historical levels.

I want to help!

Fly to an Asteroid!

Travel to Bennu on the OSIRIS-REx spacecraft!

Send your name

Join the New Millennium Committee

Let’s invent the future together!

Become a Member

Connect With Us

Facebook! Twitter! Google+ and more…
Continue the conversation with our online community!