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 Earth’s moon Greatest temperature range – -173°C to 427°C 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 Earth’s 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

Jupiter’s 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 10¼hr days Largest moon is Titan (bigger than Mercury)

Saturn and Titan from Cassini Space Mission 8/29/ ges/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 Earth’s 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 Neptune’s orbit Rock and ice, similar to other “plutoids” of Kuiper Belt

Minor members of the solar system Asteroids – small rocky bodies (>1km to <100km); lie between orbits of Mars and Jupiter Comets – small bodies made of rocky and metallic pieces held together by frozen gases; generally revolve around the sun in elongated orbits; found in the Kuiper Belt and Oort Cloud (shell of comets around our solar system) – Halley’s Comet visible every 76 years (2061)

Comet’s tail points away from the sun

Minor Members of the Solar System Meteoroid – a small solid particle that travels through space Meteor – what a meteoroid is called when it enters Earth’s atmosphere and burns up (shooting star) Meteorite – what a meteoroid is called when it hits Earth Origins: (1) leftover debris from the formation of the solar system; (2) material from the asteroid or Kuiper belts