1. Our Universe What it is like, how we think it started, how it evolved to its current state, and how it will end Today we will talk about:

2. First, let’s look at some of the objects we might find if we explored our Universe

3. Where do we live?

4. Where is the Earth?

5. The Solar System

6. Q: What is a STAR?

8. Our Sun is a star!

9. Stellar Facts A star is a big ball of burning gas Our Sun is a very average star When we look out into the night sky, many of the stars we see are very similar to our own sun In fact some of these stars also have planets, just like our own Solar System

10. What is this?

11. What is it made of?

13. MANY STARS

14. SOME SUN-LIKE

15. Galactic Facts Stars tend to group together to form galaxies Galaxies contain hundreds of thousands of stars At the centre of most galaxies is a massive black hole! Our sun is part of a galaxy

16. You are here!

18. Our Galaxy from the Earth

19. We live on the Earth The Earth is a planet in the Solar System, orbiting our star which we call the Sun The Sun is part of a galaxy When we look out into the sky at night, all of the stars we see are in our galaxy But our galaxy, called the Milky Way is just one of many…..

20. Galaxies: Hubble Space telescope image

21. ‘Zoom out’ - galaxies form filaments and voids

22. It is hard to comprehend the size of the Universe!

23. IN THE BEGINNING…….

24. EVERYTHING! In the beginning, all the matter in the universe existed in a incredibly hot and dense state, represented here by a tiny dot.

25. EVERYTHING! About 14 billion years ago, the matter started expanding and from this hot, dense state...the universe was growing.

26. EVERYTHING! ENERGY INCREASING, BECOMING LIKE A BOMB……. STARTS EXPANDING…..

27. Tick tick tick……

28. BOOM!

29. The Big Bang Not really an ‘explosion’ Universe expanded rapidly as a whole (Universe is still expanding today as a result of the Big Bang) Matter was created in the form of tiny particles (protons, neutrons, electrons) Too hot for normal ‘stuff’ to form (eg atoms, molecules)

31. COSMIC ‘SOUP’ The universe was a sea of tiny particles of matter.

32. PROTON NEUTRON ELECTRON COSMIC ‘SOUP’ Universe was too hot to support atoms.

33. Universe much cooler, atoms start to form….. Hydrogen, Helium, normal ‘stuff’ 300,000 Years Later…..

35. Universe is now a GAS

36. HYDROGEN HELIUM

37. Gravitational Collapse We started with a uniform gas Small regions became more dense due to the attraction between the gas particles from gravity. The denser regions had larger gravity and started to pull other particles towards them The gaseous Universe began to look ‘clumpy’

39. GRAVITY!

40. Gravitational Collapse Regions with more particles (higher density) become gas clouds Gas clouds become stars and galaxies Galaxies congregate together in filaments, groups and clusters

41. We are inside one of these galaxies, so all we see are the nearby stars. We can see other galaxies if we use a telescope

42. The Gemini Telescope

45. Future? The Universe is still expanding All galaxies are moving apart The ‘explosion’ of the big bang is still happening! It may continue expanding forever Or it may stop expanding, and fall inwards in a big CRUNCH!

46. What have we learned? The Universe started with a BIG BANG Gradually the particles were drawn together under GRAVITY to form STARS and GALAXIES due to the force of gravity. Many stars have planets around them The fate of the Universe is uncertain…

47. THE END