Formation of the Solar System How did the Solar System reach its present form? Quick FAQs: Our solar system About 4.5 billion years old Part of the Milky Way galaxy 1 star (our sun), 8 plants (formerly 9) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, (Pluto) M y V ery E xcellent M other J ust S wam U nder N ine P iers Planets divided into 2 categories Terrestrial Jovian We are here Formation of the Solar System Nebular theory a nebula is a cloud of gas and/or dust in space According to the nebular theory, the sun and planets formed from a rotating disk of dust and gases within the Milky Way galaxy The Milky Way We can see the edge of our Milky Way galaxy from Earth (on a clear dark night) Orbits of the planets The Terrestrial planets The 4 planets closest to the Sun Mercury, Venus, Earth, and Mars Small and rocky Thin layer of atmosphere The Jovian planets Huge gas giants (not solid) 4 planets beyond the asteroid belt Jupiter, Saturn, Uranus, and Neptune Very thick atmospheres of hydrogen, helium, methane, and ammonia Scale of the sun and planets Mercury: the innermost planet Smallest planet in the solar system barely larger than Earths moon Greatest temperature range -173C to 427C Quickest revolution, but slower rotation One rotation is 59 days Venus: the veiled planet Takes longer to rotate than to orbit the sun! Similar in size to Earth Atmosphere is 97% CO 2 Atmospheric pressure is 90 times that of Earth Covered in thick clouds that visible light cannot penetrate Mars: the red planet Thin atmosphere ~1% as dense as Earths Surface covered in rust (iron oxide) Some areas show drainage patterns similar to stream patterns on Earth Polar ice caps of frozen CO 2 Early image of the Martian surface from the Mars Rover Curiosity 8/23/2012 Jupiter: giant among giants Largest planet and fastest rotation Great Red Spot (giant storm), light and dark cloud bands At least 28 moons (biggest are Io, Callisto, Europa, Ganymede) Very faint ring system Jupiters Largest Moons Saturn: the elegant planet Would float in water! Rings are ice, dust, rocks Very windy (up to 1800 kph) 29 year revolution; but 10hr days Largest moon is Titan (bigger than Mercury) Saturn and Titan from Cassini Space Mission 8/29/2012ges/cassini/main/index.html Uranus: the sideways planet Tilted on axis 90 degrees Very faint ring system usually not visible Methane gas gives the bluish color Neptune: the windy planet High winds (up to 2100 kph) Largest moon is Triton; nearly the size of Earths moon 30.1 AUs from the sun Coldest planet (-218 C; -360 F) Takes years to orbit the sun Dwarf planet Pluto Erratic orbit that sometimes goes inside Neptunes orbit Rock and ice, similar to other plutoids of Kuiper Belt Minor members of the solar system Asteroids small rocky bodies (>1km to