Solar System

Planets These are the nine planets that we all are aware of.

Grouping of Planets Inner Planets: Mercury, Venus, Earth and Mars and the planets closest to the sun These four planets are TERRESTRIAL planets They are small and their densities are high

The Planets Mercury - Closest to sun - Smallest planet - No atmosphere - Large differences in temperature between night and day Roman god of commerce and messenger of the gods; identified with the Greek Hermes

The Planets Venus - similar in size and composition to Earth - Thick atmosphere of Carbon Dioxide (can reflect sunlight) - has flat areas, volcanoes, lava flows and rifts - brightest planet in the sky Venus was the goddess of love, sex, beauty, and fertility. Roman Venus had many abilities beyond the Greek Aphrodite; she was a goddess of victory, fertility, and even prostitution.

The Planets Earth - only life discovered in the universe so far - only planet with water in three phases - atmosphere of nitrogen and oxygen - Shape of surface is constantly changing The mother goddess was one of the deities who governed the universe before the Titans existed

The Planets Mars - Iron in rocks gives it red colour - surface has large volcanoes and deep craters - Thin atmosphere of carbon dioxide - Has two polar ice caps - Has dust storms that cover whole planet In early Roman times he was a god of agriculture, but in later religion (when he was identified with the Greek Ares) he was primarily associated with war.

Grouping of Planets Outer Planets: Jupiter, Saturn, Uranus and Neptune are much further away from the sun These planets are also called the GAS GIANTS They are large and have low densities because their atmospheres are made up of hydrogen and helium

The Planets Jupiter (Greek: Zeus) - largest planet - “Great Red Spot” is visible from Earth - spot is a storm of hydrogen and helium gas - turns on its axis every 10 hours - has 63 moons

The Planets Saturn - Identified by 1000 separate elaborate rings - Rings are very wide but very thin - Planet is composed mostly of Helium and Hydrogen Roman mythology: God of agriculture Greek: Ruler of the Titans (Kronos) Cronus was the son of Uranus and Gaea

The Planets Uranus - Gets its blue colour from Methane gas atmosphere - Rotates on its side - has rings of ice and dust - has winds that blow up 500 km/h Greek: God of sky, father of titans; ruler of the universe Roman: Caelus

The Planets Neptune - has a very faint ring system - composition and colour are similar to Uranus - has storm spots similar to Jupiter but they appear and disappear more frequently Neptune was the name that ancient Romans gave to the Greek god of the sea and earthquakes, Poseidon

PLUTO Recently demoted from planet to dwarf planet Pluto has an eccentric orbit and sometimes is closer to the sun than Neptune Roman god of the underworld and the judge of the dead. Pluto is an alternative name for the Greek god Hades

Satellites “Moons” Planet Number of known moons Mercury Venus Earth 1 All planets except Mercury and Venus have one or more objects orbiting around them Astronomers call these satellites Planet Number of known moons Mercury Venus Earth 1 Mars 2 Jupiter 63 Saturn 60 Uranus 27 Neptune 13 Pluto 3