THE PLANETS Presented by: Chelsea Brittingham

MERCURY  Mercury is the closest planet to the Sun and is also the smallest of the eight planets in our solar system.  Every seven years or so, Mercury can be seen from Earth passing across the face of the Sun.  It is named for the Roman god Mercury, the messenger to the gods – most likely related to the orbiting speed of the planet.

VENUS  Venus is the third brightest object in Earth's sky after the Sun and Moon.  Referred to as the sister planet to Earth, because their size and mass are so similar.  Due to the slow rotation on its axis, it takes 243 Earth-days to complete one rotation.

EARTH  Earth is the largest of the terrestrial planets.  Earth is the only planet not named for a mythological god or goddess.  This effect on the Moon means it is tidally locked to Earth – its rotation period is the same as its orbit time so it always presents the same face to Earth.  Earth’s atmosphere is composed of 78% nitrogen, 21% oxygen, and trace amounts of other gases including argon and carbon dixoide.

MARS  Mars is sometimes called the Red Planet because of the brownish-red color of its surface.  The tallest mountain known in the solar system is on Mars. Olympus Mons is a 21 km high and 600 km diameter shield volcano that was formed billions of years ago. Scientists have found a lot of recent evidence of volcanic lava which suggests Olympus Mons may still be active.  It takes Mars 687 Earth days to orbit the Sun with its orbit radius of 227,840,000 km.

ASTROID BELT  The asteroid belt is roughly located between the orbits of the planets Mars and Jupiter, and this region is where the vast majority of asteroids.  Around half of the mass of the entire asteroid belt is comprised of the asteroids Ceres, Vesta, Pallas and Hygiea.  Because the asteroid belt is between the Mars and Jupiter orbits, it is around 2.2 to 3.2 Astronomical Units (AU) from the Sun.

JUPITER  Jupiter has a mass of 1.90 x 1027 kg and a mean diameter of 139,822 km, Jupiter is easily the largest and most massive planet in the Solar System.  Jupiter has 67 confirmed moons orbiting the planet. They are separted into three categories, inner moons, Galilean moons, and outer moons.  Jupiter has the shortest day of the eight planets. Jupiter rotates very quickly, turning on its axis once every 9 hours and 55 minutes.

SATURN  Saturn is one of five planets able to be seen with the naked eye.  The most common nickname for Saturn is “The Ringed Planet”, a nickname arising from the large, beautiful and extensive ring system that encircles the planet.  Saturn is the least dense planet in the solar system. It is made mostly of hydrogen and has a density which is less than water – which technically means that Saturn would float.  Saturn has 150 moons and smaller moonlets.

URANUS  It takes Uranus 84 Earth days to orbit the Sun.  Uranus is often referred to as the “ice giant”. While it has a hydrogen and helium upper layer like the other gas giants, Uranus also has an icy mantle which surrounds its rock and iron core.  The Voyager 2 is the only spacecraft to have flown by Uranus. This happened in 1986 and it flew past the planet at a distance of around 81,500 km. This mission returned the very first close-up images of the planet, its ring system and its orbiting moons.

NEPTUNE  Due to its blue coloration, Neptune was named after the Roman god of the Sea.  Neptune also has a second storm called the Small Dark Spot. This storm is around the same size as Earth’s moon.  Neptune has an average surface temperature of -214°C – approximately -353°F.  The climate on Neptune is extremely active. In its upper atmosphere, large storms sweep across it and high-speed solar winds track around the planet at up to 1,340 km per second.

REFERENCE  Information: theplanets.org/theplanets.org/  Pictures: theplanets.org/theplanets.org/