The Big Bang!

1. The Big Bang!

2. The Expanding Universe How do astronomers know the universe is expanding? What is the Big Bang Theory & what evidence supports it? How can dark matter be detected?

3. Origins • How and when did the: • Universe form? (Today) • Solar system / Earth form? (Next week) • Moon form? (Next week) How Do We Know?

4. Hubble’s Law = The farther a galaxy is away from us, the faster it is moving away from us The Universe is EXPANDING! Evidence: The Doppler Effect (Wavelengths appear to change based on the motion of objects)

5. Doppler Effect • Red Shift - If waves move away from you … the waves stretch out or get longer. Objects moving away from us in space appear to be red in color. • Blue Shift - If waves approach you … the waves bunch up on top of one another … or shorten. Objects moving away from us in space appear to be red in color.

6. Doppler Effect RED SHIFT – a shift in absorption lines of star spectrum to the red wavelengths Objects moving away have longer wavelengths (red) BLUE SHIFT Objects moving towards us have shorter wavelengths (Blue) A B Which spectrum is from a star/galaxy that is moving away from us?

7. What does this spectrum tell you about the motion of the supercluster of galaxies?

8. Red Shifts • www.usask.ca/.../109_122_A/Age_Universe.htm What is going on here?

9. Red Shifted Spectrums Which galaxy is farthest from us? Which galaxy is moving away from us faster?

10. Hubble’s Law More distant galaxies have GREATER RED SHIFTS – They are moving away from Earth with faster velocity than closer galaxies. The UNIVERSE IS EXPANDING!

11. Big Bang Theory The universe came into being at a single moment, in an event called BIG BANG. All matter & energy of universe were concentrated into an incredibly hot, small, mass. An enormous explosion sent matter and energy out into space. When: 15-20 billion years ago

12. Support for Big Bang • Red Shifts tell us Galaxies are ACCELERATING AWAY from a center (Expanding) 2. COSMIC Microwave BACKGROUND RADIATION Detected in 1965Faint radiation coming from all directionsBelieved to be energy from Big Bang

13. Evidence for Big Bang • Red shift - as light from distant galaxies approach earth there is an increase of space between earth and the galaxy, which leads to wavelengths being stretched • In 1964, Arno Penzias and Robert Wilson, discovered a noise of extraterrestrial origin that came from all directions at once - radiation left over from the Big Bang • In June 1995, scientists detected primordial helium in the far reaches of the universe - consistent with an important aspect of the Big Bang theory that a mixture of hydrogen and helium was created at the beginning of the universe

14. Background Cosmic Microwave Radiation What? • Microwaves coming at us from everywhere, but no where specific. • It’s lingering energy (echo) from Big BANG explosion!

15. Fate of Universe • Expand forever / Galaxies drift apart? OR B. “Big Crunch” – Galaxies collapse into a center? Depends on how much mass there is in the universe … which is in dispute.

16. Dark Matter Dark Matter = Does not give off radiation & cannot be detectedExerts gravitational force on visible matterUniverse may be 90% + dark matter Why do we think Dark Matter exists? Galaxies are accelerating faster than they should be (based on the observable matter in the Universe). The acceleration due to gravity does not match up with the amount of matter that we can see. A = F/m (F = ma rearranged) tells us that there must be more mass … we’re just not seeing it.

17. Questions • What theory states that the universe began as an explosion of an incredibly dense point of matter 2. According to the theory of Big Bang, how old is our universe? • Our universe is currently … a. Contracting b. Expanding c. Staying the same

18. Questions • What theory states that the universe began as an explosion of an incredibly dense point of matter Big bang 2. According to the theory of Big Bang, how old is our universe? 15-20 billion years • Our universe is currently … a. Contracting b. Expanding c. Staying the same

19. 4. What does Hubble’s Law say about the motion of galaxies? • When scientists look at the spectrum for Andromeda, our neighboring galaxy, they notice that the lines are moved over to the blue end of the spectrum. Andromeda is … • Moving towards us. • Moving away from us. • A constant distance from us. • Not moving.

20. 4. What does Hubble’s Law say about the motion of galaxies? Hubble’s Law = The farther a galaxy is away from us, the faster it is moving away from us • When scientists look at the spectrum for Andromeda, our neighboring galaxy, they notice that the lines are moved over to the blue end of the spectrum. Andromeda is … • Moving towards us. • Moving away from us. • A constant distance from us. • Not moving.

21. Quasars, are very distant galaxies. When scientists look at quasars with a spectroscope they would see the lines on their spectrum shifted to the (RED / BLUE) end of the spectrum. 7. How does the red – shift of far away galaxies support the big bang theory?

22. Quasars, are very distant galaxies. When scientists look at quasars with a spectroscope they would see the lines on their spectrum shifted to the(RED / BLUE) end of the spectrum. • How does the red – shift of far away galaxies support the big bang theory? Red Shifts tell us Galaxies are ACCELERATING AWAY from a center (Expanding)

23. 8. What kind of wavelength on the electromagnetic spectrum is lingering around like an echo from the Big Bang? • What are two possible scenarios for the future of the universe?

24. What kind of wavelength on the electromagnetic spectrum is lingering around like an echo from the Big Bang? COSMIC Microwave BACKGROUND RADIATION Detected in 1965Faint radiation coming from all directionsBelieved to be energy from Big Bang • What are two possible scenarios for the future of the universe? • Expand forever / Galaxies drift apart? OR B. “Big Crunch” – Galaxies collapse into a center? Depends on how much mass there is in the universe … which is in dispute.

25. What is dark matter and how much of the universe do scientists think may be dark matter?

26. What is dark matter and how much of the universe do scientists think may be dark matter? Dark Matter = Does not give off radiation & cannot be detectedExerts gravitational force on visible matterUniverse may be 90% + dark matter

27. Features of Our Solar System • in a spiral arm of the Milky Way Galaxy • Sun • 9 planets • 101 known moons (satellites) • a tremendous number of asteroids • most orbit the Sun between the orbits of Mars and Jupiter • millions of comets and meteorites • interplanetary dust and gases

29. Relative Sizes of the Sun and Planets

30. Solar System Configuration

31. Origin of Our Solar System Solar nebula theory • cloud of gases and dust • formed a rotating disk • condensed and collapsed due to gravity • forming solar nebula • with an embryonic Sun • surrounded by a rotating cloud

32. Embryonic Sun and Rotating Cloud • planetesimals have formed in the inner solar system • large eddies of gas and dust remain far from the protosun

33. The Planets • Terrestrial Planets • Mercury • Venus • Earth • Mars • small, composed of rock, with metal cores • Jovian Planets • Jupiter • Saturn • Uranus • Neptune • large, composed of hydrogen, helium, ammonia, methane, relatively small rocky cores – Pluto?