PlanetsBy: Zach Miller

and Ashley Dwyer

The Sun

• Our Sun is one of more than 100 billion stars in our galaxy.

• The Sun is, at present, about 70% hydrogen and 28% helium by mass. Everything else ("metals") amounts to less than 2%.

• There are nine planets and a large number of smaller objects orbiting the Sun.

Mercury

• Mercury is the closest planet to the Sun and the eighth largest.

• Mercury has no known satellites.

• Mercury is often visible with binoculars or even the unaided eye.

• Temperature variations on Mercury are the most extreme in the solar system ranging from 90 K to 700 K.

Venus

• Venus is the second planet from the Sun and the sixth largest.

• Venus' orbit is the most nearly circular of that of any planet.

• Venus probably once had large amounts of water like Earth but it all boiled away. Venus is now quite dry.

• Venus has no satellites and is usually visible with the unaided eye.

Earth

• Earth is the third planet from the Sun and the fifth largest.

• Earth is the only planet whose English name does not derive from Greek/Roman mythology.

• The Earth is the densest major body in the solar system.

• 71 Percent of the Earth's surface is covered with water.

• Earth has only one natural satellite, the Moon.

Mars

• Mars is the fourth planet from the Sun and the seventh largest.

• Mars' orbit is significantly elliptical.

• The average temperature on Mars is about 218 K.

• Mars has two tiny satellites which orbit very close to the martian surface.

Jupiter

• Jupiter is the fifth planet from the Sun and by far the largest.

• Jupiter is more than twice as massive as all the other planets combined.

• Jupiter is about 90% hydrogen and 10% helium.

• Jupiter has 63 known satellites.

Saturn

• Saturn is the sixth planet from the Sun and the second largest.

• Saturn's rings are extraordinarily thin: though they're 250,000 km or more in diameter they're less than one kilometer thick.

• Saturn has 30 named satellites plus one discovered in 2003 and is unnamed as of yet.

Uranus

• Uranus is the seventh planet from the Sun and the third largest (by diameter).

• Uranus is composed primarily of rock and various ices.

• Uranus has 11 known rings which are all very faint.

• Uranus has 21 named moons and six unnamed ones.

Neptune

• Neptune is the eighth planet from the Sun and the fourth largest.

• Neptune has an internal heat source - it radiates more than twice as much energy as it receives from the Sun.

• Neptune's rings are very dark but their composition is unknown.

• Neptune has 13 known moons.

Pluto

• Pluto is the farthest planet from the Sun and by far the smallest

• Pluto is the only planet that has not been visited by a spacecraft.

• There are some who think Pluto would be better classified as a large asteroid or comet rather than as a planet.

• Pluto has only one known satellite.