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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

Hayabusa2 image of Earth and the Moon, November 26, 2015

Hayabusa2 image of Earth and the Moon, November 26, 2015

Hayabusa2 used its optical navigation telephoto camera (ONC-T) to capture this view of Earth and the Moon together on November 26, 2015 at 03:46 UT, or 12:46 Japan time. The image is made of three distinct images captured through red, green, and blue filters, and has been processed to align the different-filter images with each other. North is to the left; Asia and Australia are visible on the lit face of Earth. Hayabusa2 was on the way in to its December 3, 2015 flyby of Earth.

Filed under pics of Earth by planetary missions, pretty pictures, Hayabusa2, amateur image processing, Earth, the Moon, many worlds

Earth and the Moon from PROCYON

Earth and the Moon from PROCYON

PROCYON captured this photo of Earth and the Moon together from a distance of 8 million kilometers on November 16, 2015.

Filed under pics of Earth by planetary missions, pretty pictures, Hayabusa2, Earth, the Moon, many worlds

Earth and Moon as seen by MESSENGER

Earth and Moon as seen by MESSENGER

This image was cropped from the MESSENGER Dual Imaging System (MDIS) full frame of the Earth and Moon captured on May 11, 2005. MESSENGER was about 29.6 million kilometers from Earth at the time that the photo was taken, approaching its August 2 flyby.

Filed under pics of Earth by planetary missions, pretty pictures, MESSENGER, Earth, the Moon, many worlds

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Section Highlights

Planetary Facts

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

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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.

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Every Round Object in the Solar System, to Scale

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

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