1. Origin of the Solar System GCSE ScienceChapter 12

2. The solar system was formed by a gravitational fall of a cloud of gas made up of hydrogen, helium and dust. Origin of the Solar System GCSE ScienceChapter 12 Next

3. Orbit of the Planets 1 The four inner planets are rocky. They are kept in an orbit around the sun by gravity. Venus Earth Mars Mercury GCSE ScienceChapter 12

4. Orbit of the Planets 2 The other planets are gas giants. Pluto is no longer considered to be a planet! Jupiter Saturn Uranus Neptune GCSE ScienceChapter 12

5. Comets A comet’s orbit is an ellipse shape. The comet’s tail always points away from the sun - why? GCSE ScienceChapter 12

6. MERCURY  No atmosphere.  Closest to the sun.  Daytime temperature 350°C.  Night time temperature - 180°C. GCSE ScienceChapter 12

7. Venus  Thick and dense atmosphere made up of sulphuric acid and carbon dioxide.  Severe greenhouse effect.  No life.  No moon. GCSE ScienceChapter 12

8. EARTH Blue planet with clouds. Oxygen and water available. Inhabited by life forms. GCSE ScienceChapter 12

9. MARS  Rocky with red dust on its surface.  May once have had water  No life found here so far. GCSE ScienceChapter 12

10. JUPITER  The largest planets (all the other planets would fit into this one!).  Atmosphere of liquid hydrogen and helium. GCSE ScienceChapter 12

11. SATURN Rings of small rocks encased in ice. GCSE ScienceChapter 12

12. URANUS  Pale green colour.  Looks as if it’s lying on its side (it has a horizontal axis). GCSE ScienceChapter 12

13. NEPTUNE  Similar to Uranus.  Blue in colour. GCSE ScienceChapter 12

14. PLUTO  Not considered to be a planet any longer.  About 1/5 of the size of the Earth. GCSE ScienceChapter 12

15. Asteroids  There is an asteroid belt between Mars and Jupiter.  These are bits of rock of varying sizes.  These are affected by the gravitational pull of the planets, and some have even collided with earth! GCSE ScienceChapter 12

16. Comets  Made up of a mixture of ice and dust.  Come from two places: Oort cloud (beyond the solar system), and the Kuiper belt (beyond Neptune).  They have elliptical orbits.  Tails always point away from the sun and are millions of kilometres long! GCSE ScienceChapter 12

17. Relative sizes GCSE ScienceChapter 12

18. Data on the Solar System Planet Diameter (km) Distance from the Sun (km ×10 6 ) Orbit (Years) Average Temperature (°C) Mercury 4900580.24350 Venus 120001080.62450 Earth 128001501.0015 Mars 68002281.88-30 Jupiter 14300078012.00-150 Saturn 120000143029.00-180 Uranus 52000280084.00-210 Neptune 490004500165.00-220 Pluto 30005900248.00-230 You are not expected to learn this information, but you will need to use the data to draw a conclusion e.g. ….. GCSE ScienceChapter 12

19. CONCLUSION: The average temperature of the planets decreases with their distance from the sun. Venus is an exception due to the greenhouse effect. The change is not constant. GCSE ScienceChapter 12

20. CONCLUSION: The time it takes for planets to orbit the sun increases with distance. The change is not constant. GCSE ScienceChapter 12

21. GRAVITY  Gravity is the force that exists between two or more masses.  Gravitational force always attracts mass.  Approximately 1/1,000,000 N exists between you and the person next to you (it’s not strong enough to affect us). GCSE ScienceChapter 12

22. Gravity The earth has a lot of mass, so its gravitational attraction on our bodies keeps us on the ground. GCSE ScienceChapter 12 A

23. GRAVITY  Gravity is the force that keeps the planets in orbit around the sun.  Gravity i the force that keeps the moon (the earth’s natural satellite) in its orbit around the earth.  Gravity is the force that keeps satellites in their orbits around the earth.  Gravity always act on the centre of a mass. GCSE ScienceChapter 12

24. GRAVITY If it’s possible to fire a gun quickly enough, then the gravitational force that pulls the bullet down towards the centre of the earth, causes it to orbit around the earth. GCSE ScienceChapter 12

25. GRAVITY - SUMMARY  A small body keeps in orbit around a larger body because of its high mass, and the gravitational force between the two bodies.  The larger the distance between the two bodies, the weaker the gravitational force.  The greater the mass, the greater the gravity. Gravity meter GCSE ScienceChapter 12

26. DISCOVERING NEW PLANETS  A planet’s orbit is something that can be predicted, but sometimes a planet shows a change in its path. Sometimes, the gravitational pull of another planet affects its path.  We have been able to use this sin our search for new planets.  April 24, 2007 – a planet similar to earth, 20.5 light years away, was found, with a larger gravity (1.6 more than earth). The effect of another planet’s gravity GCSE ScienceChapter 12