Exploring Our Solar System: Planets, Stars, and Galaxies

1. Foundations of Astronomy Science and Religion in Schools Project - Unit 4aThe Scientific Account of the Beginning

2. The Sun • Ball of super-hot gas • Core temperature 16 million degrees ºC • Roughly 4.5 billion years old • Will last another 4.5 billion years • A very typical star

3. The Solar System • In this image, the planets are in the correct order • The relative sizes of the planets is about right, but the distances are not • The Sun is the arc on the far left!

4. Mercury • 0.4 times Earth’s diameter • No atmosphere worth mentioning • Surface temperature 1700C on average • Mercury rotates two times for every three orbits round the Sun • Takes 88 days to orbit the Sun • Distance from the Sun is about 0.4 times that of Earth

5. Venus • Clouds are too thick to see the surface • Venus is bright as these clouds reflect a lot of the sun’s light • Surface of Venus is hot (4600C) • Atmospheric pressure is about 90 times that on Earth • Surface features only ‘seen’ by radar

6. Guess where?

7. Meteorites • Lumps of rock from space that generally burn up in the atmosphere • Some large ones make it to the surface and can cause damage

8. The Moon • Orbits the Earth • No atmosphere • Some water, as ice • Craters due to being hit by meteorites • Probably made when a giant meteor hit the Earth and blasted part of the crust into space

9. Phases of the Moon • Moon keeps the same face to the Earth • Time it takes to turn on its axis, same as the time taken to orbit Earth • Phases dependent on how much of the Moon visible from Earth is lit by the Sun

10. Mars • Atmosphere is carbon dioxide • Atmospheric pressure is 0.75% of Earth’s • Smaller than Earth, but about the same size of land area • Being well explored by unmanned probes

11. Martian Surface

12. Olympus Mons • Olympus Mons is the large volcano in the top left • The pale features are clouds drifting over the region

13. Jupiter • Largest planet in the solar system • Composed entirely of gas • Black dot is the shadow of Europa • Large red dot is a hurricane - bigger than Earth • 11 times the diameter of Earth and a thousand times more massive

14. Saturn • Beautiful gas giant • Nearly as big as Jupiter • Ring system can clearly be seen from Earth with even a small telescope

15. Complex structure of rings Large gap is the Cassini division The F ring contains shepherd moons The Moons lap each other every 25 days Can cause the rings to be ‘braided’ Saturn’s rings

16. True colour image from Voyager 2 makes Uranus seem bland Infra-red image from the Hubble Space telescope shows more activity and the thin ring system Hubble image shows cloud structure Also that Uranus rotates on it side - so it ‘rolls’ around the Sun, unlike the other plants Uranus

17. Neptune • Final gas giant • Similar in size to Uranus • Great dark spot was thought to be a storm system, but could be a ‘hole’ like the hole in Earth’s ozone layer • High altitude ‘wispy’ clouds can also be seen

18. Pluto • Pluto’s orbit crosses that of Neptune • Also highly angled with respect to the other planets • Pluto’s moon Charon was discovered in 1978

19. New planet? • Discovered on 14 November 2003 • Far beyond Pluto • Orbit yet to be worked out • Status as a planet to be determined (is it big enough?) • Provisionally called Sedna, the Inuit goddess of the sea, who was believed to live in the cold depths of the Arctic Ocean

20. The Milky Way

21. Andromeda Galaxy • Nearest galaxy to the Milky Way • Still about 2 million light years away • In about 3 billion years, Andromeda will collide with our galaxy • Can be seen with the naked eye on a dark night

22. Deep Field • One of the most important pictures ever taken • Hubble space telescope • Try to count the number of galaxies! • This patch of sky could easily be covered by the end of your finger at arm’s length