Planets in the Solar System

• Planet is a celestial body that orbits the sun or other stars.
• The word planet comes from the Greek word “planetes” which means “wanderer.”
• Sun's gravity pull planets in an orbit around it.
• Mercury is closest planet to the sun.
• Mercury takes 88 days to revolve around the sun.
• Revolution is to orbit around another celestial body, while rotation is to rotate around the axis.
• Mercury has the thinnest exosphere in the solar system. It's made of oxygen, sodium, hydrogen, helium, and potassium.
• The name Mercury came from the messenger of god.
• Venus is the hottest planet in the solar system due to its thick atmosphere of carbon dioxide which traps the heat.
• Venus is also called earth's twin or morning or evening star.
• The name venus came from the Roman goddess of love and beauty because of its shining appearance in the sky.
• Earth was formed 4.5 billion years ago from a mixture of dust and gas. It grew larger due to collisions of dust particles, asteroids, and other growing planets, including one last giant impact that threw enough rock, gas, and dust into space to form the moon.
• The name earth came from the Old English words 'eor(th)e' and 'ertha'. In German it is 'erde'.
• Mars is the red planet since the iron minerals in its soil oxidize or rust, making it look red.
• The name Mars came after the Roman god of war. It's because the red resembles blood.
• The Great Red Spot is big spinning storm on Jupiter.
• Jupiter has 95 moons.
• Jupiter's fast rotation drives electric current in the great red spot giving it great magnetic field.
• The name Jupiter came from the king of Roman gods.
• Saturn is the 2nd largest planet in the solar system.
• Saturn's ring is made of ice.
• Saturn is a gas giant made of hydrogen and helium.
• The name Saturn came after the Roman god of agriculture who was the father of Jupiter.
• Uranus is an ice giant.
• Uranus has a thick atmosphere made of methane, hydrogen, and helium.
• Uranus is the only planet that spins on its side.
• The name Uranus came from the Greek god of the sky.
• Neptune is blue to the methane in its atmosphere. It absorbs red light which makes it appear darker.
• Neptune orbits in an oval shape.
• Neptune is 4.5 billion km away from the sun.
• Neptune takes 165 earth years to revolve around the sun.
• Neptune is the first planet to be discovered through mathematical equations. Through predictions by Urbain Le Verrier, Johanne Galle discovered Neptune in 1846.
• The name Neptune came after the Roman god of the sea, as suggested by Urbain Le Verrier.
• Mercury, Venus, Earth, and Mars are inner planets while Jupiter, Saturn, Uranus, and Neptune are outer planets.
• Inner planets have shorter revolutions, less moons, and usually composed of rock and metal.
• Outer planets have longer revolutions, more moons, and mostly made up of gas.
• Ganymede, Europa, Io, and Callisto are the 4 major moons of Jupiter.
• Ganymede is Jupiter's largest moon.
• Christiaan Huygen discovered the first moon of Saturn, Titan, in 1655.
• Titan is Saturn's largest moon.