The Electromagnetic Spectrum in our Universe

1. The Electromagnetic Spectrum in our Universe

2. Background info. • Everything astronomers know about the universe comes from studying light from distant stars and nebula. • The universe is full of energy, visible and invisible, all of these different energies are called electromagnetic radiation.

3. Background info. • All these different energies are classified according to wavelength and frequency. • This info. is displayed as the Electromagnetic Spectrum.

4. Background info. How do we know this? Instruments detect their presence.

5. Electromagnetic Spectrum draw this

6. Sir Isaac Newton discovered that when light passes through a prism, the different colors of light are broken up. each color has its own wavelength

7. So...what’s a rainbow?

8. Speed of light: 300,000 km/sec or 186,000 mi/sec • Visible light only makes up a small part of different types of energy known as electromagnetic radiation • Gamma waves and radio waves are different due to their wavelengths

9. short waves long waves Which have the highest energy?

10. Spectroscopy • study of the properties of light that depend on its wavelength • when the light of a star is studied there are spectral lines • the spectral lines act as a “fingerprint” that helps to identify the elements inside the star (a star’s chemical composition)

11. Emission spectrum of Hydrogen, H Emission spectrum of Iron, Fe

12. optical telescopes, radio and x-ray telescopes are used to collect data

13. radio telescope xray telescope

14. The Expanding Universe • The Doppler Effect is used to determine if a galaxy is moving away from ortowards earth

15. Electromagnetic Spectrum Compare red and blue visible light... Does red have a long or short wavelength? Does blue have a long or short wavelength?

16. Doppler Effect works with sound waves and light waves the siren in front of the cop car has a high pitch, but behind the car it has a low pitch sound draw this If we could see the sound waves, what color would they be?

17. If a galaxy is moving toward earth, is it blue or red? If a galaxy is moving away from earth, is it blue or red?

18. 1929 Edwin Hubble discovered that the universe is expanding • galaxies are moving away because they appear red ( the waves are stretched out) • most of the galaxies we see have a Red Shift

19. Hubble’s Law: galaxies are moving away from earth at a speed that is proportional to their distance

20. Hubble’s Law • Distant galaxies are moving away from each other faster than those that are closer together

21. as the dough rises, raisins that were farther apart travel a greater distance in the same time as those that were closer together, raisins are like galaxies in an expanding universe

22. Review #1Which EM waves are long and stretched out? • radio waves

23. Review #2 What color waves are long and stretched out? • red waves

24. Review #3Which EM waves are short and squished? • gamma rays

25. Review #4What color waves are short and squished? • violet waves

26. Review #5 What information is found by looking at the spectral lines from a star’s gases? • which elements are in the star (chemical composition)

27. Review #6 What is happening to the size of the universe? • universe is expanding

28. Review #7 What kind of shift is responsible for this? • Red shift

29. Review #8 What does Hubble’s Law explain? • galaxies are moving away at a speed that is proportional to their distance