All About the Planets

The Sun, Earth and Planets are found in the Orion arm.

The gaseous planets are low density gas giants. Jupiter, Saturn, Uranus and Neptune are the four gaseous planets. These planets are also called the Jovian planets.

Jupiter is the 5th planet from the sun and is the largest planet. This gas giant has a mass that is two and a half times larger than the mass of the other planets combined.

Image of Jupiter taken from Voyager Space Craft

Saturn is the 6th planet from the Sun and the 2nd largest after Jupiter. Along with Jupiter, Neptune and Uranus, Saturn is known as a gas giant. Saturn's interior consists of a small core of rock and ice that is surrounded by a thick layer of hydrogen. It's prominent rings are mostly made up of ice crystals.

Saturn's rings as seen by a passing spacecraft.

Pictured here is a close up of Saturn's rings, which are made up of ice particles, and small amounts of rocky debris and dust.

Uranus is the 7th planet from the Sun and is the 3rd largest. It is named after the Greek deity of the sky. Uranus is the first planet to be discovered by the telescope.

Neptune is the 8th and furthest planet from the sun. It is named for the Roman god of the sea. It is the 4th largest planet and has a mass 17 times that of Earth. Neptune was discovered through a mathematical formula rather than by observation. Similar in composition to Uranus.

The other four planets are terrestrial planets. These are Mercury, Venus, Earth and Mars. For the most part these planets are composed of rocks (Earth is the exception).

Earth is the 3rd planet from the Sun and is the 5th largest in the solar system. Home to humans and many species, earth is the only known place in the universe where life exists. It is the largest of the terrestrial planets and is referred to as "the world."

Mars is the 4th planet from the sun. It is named after Mars, the Roman god of war. It is also called the "Red Planet" because of its red appearance. Mars has a thin atmosphere which has features similar to Moon craters and volcanoes, deserts and polar ice caps. Mars is the site of Olympus Mons, the highest known Mountain in the Solar System.

Mars photo taken by Hubble Space Telescope

Venus is the 2nd largest planet to the sun. It orbits the sun every 225 days. It is named after the Roman goddess of love. Venus is 2nd only in brightness after the moon ( in the night sky). Venus is sometimes called Earth's sister because the two planets are similar in size, gravity and composition.

Mercury is the innermost planet and smallest planet in the Solar System. Mercury orbits the sun once every 87 days or so. It is similar in appearance to the earth's moon and has the highest eccentricity of all the planets.

Pluto is now considered to be the second largest dwarf planet. It is about .66% of the size of Earth.