11.2 solar system

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1. 11.2 The Solar System 2. Solar System A planet is a celestial body that orbits one or more stars Large enough that gravity holds it in a spherical shape Is the only body occupying the orbital path Only reflects light radiated by its star (does not generate its own light) A solar system is a group of planets circling one or more stars 3. Formation of the Solar System Our Sun formed 4.5 billion years ago Dust and gases from the Sun's formation combined to form the planets Not all planets formed at the same time - material closest to the Sun formed first Inner or terrestrial planet Mercury, Venus, Earth, Mars Solid cores & rocky crusts Farther away, large clumps or gas, ice, and dust formed the outer or Jovian planets Jupiter, Saturn, Uranus, Neptune Large, gaseous & cold 4. Rotation and Revolution Planets spin on an axis Rotation (DAY) Speed of 1670 km/hr Takes 24 hr to complete one rotation Planets orbit the sun Revolution (YEAR) Speed of 108000 km/hr Takes 365.25 days to complete 5. The Sun Makes up more than 99% of the mass of out solar system 110 Earths fit across the diameter of the Sun Mostly hydrogen gas Fusion reactions H He produce heat and light 6. Solar Wind Hot gas is ejected from the corona in a sudden burst High energy particles rush towards Earth creating an effect called a solar wind Earth's magnetic field deflects the solar wind around the planet protecting us from its fatal effects Some particles enter our atmosphere at the poles producing the Northern /Southern Lights 7. Planets 8. Planet Criteria Orbit one or more stars Large enough that its own gravity holds a spherical shape Be the only body occupying the orbital path Pluto has other similarly sized object from the Kuiper belt sharing its orbit 9. Astronomers compare distances in space using astronomical units 1 AU = Average distance from Earth to Sun 1 AU 150 million km 10. Structure of the Solar System In addition to the 8 planets orbiting our sun there are numerous other small celestial bodies Moons: Every planet except Mercury and Venus have one or more moons So far 150 moons have been discovered in our solar system 11. Asteroids: Small rocky bodies left over from the formation of the solar system Most orbit the sun between Mars and Jupiter Comets: Made of ice, rock and gas (dirty snowball) Originate from the Kuiper belt and Oort Cloud Orbit the sun in large irregular orbits When a comet gets close to the sun the heat from the sun causes some of the ice to evaporate forming a tail 12. Trans-Neptunian Objects (Kuiper Belt) Left over from the formation of the solar system Orbiting sun past Neptune Contains many dwarf planets (inc. Pluto) Oort Cloud Spherical cloud of dust, ice and gas Furthest reaches of the suns gravity Origin of many comets