Meet the planets: our solar system's roster

Below is a montage of planetary photos taken by exploratory spacecraft. Click it to see the full size image. These are actual pictures, not computer generated graphics*.

Included are (from top to bottom) Mercury, Venus, Earth and Moon, Mars, Jupiter, Saturn, Uranus and Neptune.

• Mercury image was taken by Mariner 10
• Venus image by Magellan
• Earth and Moon images by Galileo
• Mars image by Mars Global Surveyor
• Jupiter image by Cassini
• Saturn, Uranus and Neptune images by Voyager
• Pluto is not shown as it is not a planet and no spacecraft has yet visited it. (Sorry Pluto supporters. But fear not - New Horizons is on its way to the Dwarf Planet as we speak!)

*The image of Venus has been rendered based on collected data. The atmosphere of this planet is too thick to see the surface.

The closest to the sun, this small planet zips around in an eccentric orbit. It doesn't circle the sun, it... ovals it. An eccentric orbit means Mercury travels along an uneven, elliptical path.

The statistics

Composition: Rock; Iron Core

Atmosphere: Thin and unstable

Rotation: One day is 58.7 Earth days

Revolution: One year is 88 Earth days

Gravity: A 100 lb person would weigh 38 lbs on Mercury

Moons: NO

Rings: NO

Alien Life: NO

Special Achievement: FASTEST PLANET!

Mercury Quick Fact: If you were standing on Mercury, the Sun would look three times as big as it does from Earth.

Shrouded by a heavy, cloudy atmosphere, Venus is a traveling greenhouse. The pictures you see here of the planet are composite images, taken from multiple craft and telescopes. The surface of the planet is not visible through the clouds of sulfuric acid that are miles deep.

The statistics

Composition: Rock; Nickel/Iron Core

Atmosphere: Very heavy

Rotation: One day is 243 Earth days

Revolution: One year is 224.7 Earth days

Gravity: A 100 lb person would weigh 91 lbs on Venus

Moons: NO

Rings: NO

Alien Life: NO

Special Achievement: HOTTEST PLANET!

Venus Quick Fact: The Sun Also Rises... in the WEST. Venus has a retrograde rotation; it is spinning backwards. If that is not rebellious enough, this planet's day is longer than its year! It orbits the sun faster than it rotates on its axis.

Home sweet home! Earth is the only planet whose water is a liquid on the surface. As scientists search outside our solar system for exoplanets that may have life, liquid water is the first thing they look for.

The statistics

Composition: Rock/Water; Iron Core

Atmosphere: Lovely

Rotation: One day is 24 hours

Revolution: One year is 365 days

Gravity: A 100 lb person weighs 100 lbs at sea level

Moons: YES. One: Luna. Why don't people call the moon by its name? It's like naming your dog Rover, then just calling him "the dog".

Rings: NO

Alien Life: Reports are conflicting.

Special Achievement: LIQUID PLANET!

Earth Quick Fact: When you look at a map of Earth, you are seeing a distorted image; the truth is that seventy-one percent of its surface is covered with water.

Mars no longer has an active tectonic system. But it sure used to...Olympus Mons, now dormant, is the largest volcano in the solar system. The largest canyon also belongs to Mars: Valles Marineris.

The statistics

Composition: Rock; Iron Core

Atmosphere: Thin, but once was very thick

Rotation: One day is 24.6 Earth hours

Revolution: One year is 687 Earth days

Gravity: A 100 lb person would weigh 38 lbs on Mars

Moons: YES Two: Phobos, Deimos

Rings: NO

Alien Life: NO

Special Achievement: LARGEST VOLCANO!

Mars Quick Fact: Its red color comes from the iron in its core. Massive volcanic eruptions have spewed the iron across the surface of the entire planet.

Jupiter's day lasts about 10 hours. That means it is spinning at more than twice the speed of Earth. Considering that Jupiter is more than 300 times our size, it's rotation makes our own seem down right pokey.

The statistics

Composition: Gas; Molten Rock Core

Atmosphere: Very turbulent

Rotation: One day is 9.8 Earth hours

Revolution: One year is 11.8 Earth years

Gravity: A 100 lb person would weigh 254 lbs on Jupiter

Moons: YES 63! And we are finding more every time we look. The most famous are Io and Europa

Rings: YES

Alien Life: NO

Special Achievement: LARGEST PLANET !

Jupiter Quick Fact #1: It is not only the biggest planet in the solar system... Jupiter is home of the biggest STORM in the solar system. The Eye of Jupiter is a jumbo thunderstorm so big that Earth could fit right inside of it.

Jupiter Quick Fact #2: This planet contains 71% of the planetary matter in our entire solar system

Saturn's rings are made of chunks of ice, some as big as a car. The moons of Saturn help shape them and keep them in position. The Hubble telescope along with Cassini spacecraft have determined that the rings are no more than 30 feet thick!

The statistics

Composition: Gas; Molten Rock Core

Atmosphere: Very turbulent

Rotation: One day is 10.2 Earth hours

Revolution: One year is 29.5 Earth years

Gravity: A 100 lb person would weigh 108 lbs on Saturn

Moons: YES 31 and counting. The most famous is Titan

Rings: YES

Alien Life: NO

Special Achievement: LEAST DENSE PLANET !

Saturn Quick Fact: Saturn is not a heavy planet. It would actually float on water, if you could find a big enough bucket to put it in.

Uranus rotates on a parallel axis, unlike the other planets which spin perpendicular. This causes some very strange weather on the giant blue planet. Which pole is the north one? This is a great question to ask an astronomer, if you want to see him shrug.

The statistics

Composition: Gas; Molten Rock Core

Atmosphere: Thick and cloudy

Rotation: One day is 17.9 Earth hours

Revolution: One year is 84 Earth years

Gravity: A 100 lb person would weigh 91 lbs on Uranus

Moons: YES 27: All are named after Shakespeare characters

Rings: YES

Alien Life: NO

Special Achievement: SIDEWAYS PLANET!

Uranus Quick Fact: Because it rotates on its side, its poles are each exposed to the sun for half of each orbit. This means the seasons on Uranus last about 20 years.

Voyager 2 spotted a dark spot on Neptune in 1989. It was a storm, very similar to Jupiter's giant red spot.

The thunderstorm on Jupiter has been raging for 300 years, so when the Hubble telescope focused in on Neptune in 1994, it was a big surprise that the storm was gone. Hubble did spot "The Scooter", a group of very fast moving white clouds that Voyager 2 saw in 1989.

The statistics

Composition: Gas; Rock Core

Atmosphere: Very Turbulent

Rotation: One day is 19 Earth hours

Revolution: One year is 164.8 Earth years

Gravity: A 100 lb person would weigh 119 lbs on Neptune

Moons: YES 13: The most famous is Triton

Rings: YES

Alien Life: NO

Special Achievement: WINDIEST PLANET!

Neptune Quick Fact: Before anybody had seen the planet, astronomers knew it was there. Neptune's existence was predicted mathematically well before it was actually spotted with a telescope.

Exactly what did Pluto do to lose its Planet Status?

Pluto lives in the Kuiper Belt, which is similar to the asteroid belt. It is filled with objects that are as big as Pluto - or even bigger.

Several Kuiper objects have been identified which could qualify as planets, based on size. So the question was raised: Should we add half a dozen new planets to the roster? We are finding new objects in the belt all the time. What is the limit?

The International Astronomical Union gave the word "planet" is first specific definition in 2006. The definition excluded Pluto as a planet, but created a new category: Dwarf Planet.

The statistics

Composition: Rock and Ice

Atmosphere: Thin and Seasonal

Rotation: One day is 6.39 Earth days

Revolution: One year is 247.7 Earth years

Gravity: A 100 lb person would weigh 8 lbs on Pluto

Moons: YES 3: Charon, Hydra, and Nix

Rings: NO

Alien Life: NO

Special Achievement: MOST CONTROVERSY!

Pluto Quick Fact: Pluto's atmosphere is seasonal because it has an eccentric orbit. As it gets closer to the sun, the frozen elements on the dwarf planet thaw and form a thin atmosphere. When it leaves the warmth of the sun, the air once again freezes and falls to the ground.