2. Study of the universe (Earth as a planet and beyond)

5. Structure: Universe  Galaxy Superclusters  Local Group  Milky Way Galaxy  Solar System

6.  http://www.youtube.com/watch?v=66hSXdjNZ_I http://www.youtube.com/watch?v=66hSXdjNZ_I

7. 1. How many solar systems are in our galaxy? So far.. about 150 with new discoveries every year 2. How many stars are in our galaxy? 200-400 billion 4. How many galaxies are in the universe? Hubble has observed over 5000, but it is estimated that there are over 500 billion!

8. Earth to Sun: 93 million miles or 1 Astronomical unit (AU) ** 8 minutes for sunlight to reach Earth ** 8 minutes for sunlight to reach Earth Solar System (from Sun to Keiper Belt): 40 AU **takes 5 ½ hours for sunlight to reach Pluto **takes 5 ½ hours for sunlight to reach Pluto Outside of our solar the distances are so great we have to use a new unit: the light year. (LY)

9. Sun to next nearest star (Alpha Centauri): 4.3 LY Milky Way Diameter: 100,000 LY Sun to Andromeda galaxy (nearest galaxy): 2.9 million LY Limit of observable universe: about 15 billion LY

19.  Stable stars (like our sun) are called main sequence stars.  Stars are made of hydrogen that exists in a state of matter called plasma.

20.  Stars produce energy through nuclear fusion. This requires extreme heat and pressure.  A star is born when the temperature hydrogen can fuse into helium is reached (~120 million Kelvin) FUSION

21.  Fusion force outward = gravitational force inward (forces are balanced and stable)  Once the star runs out of hydrogen in the core, the star is UNSTABLE and begins to die.

23. Temperature of stars is indicated by COLOR Blue = highest energy = hottest Red = lowest energy = coolest

24. Luminosity (actual brightness) is impacted by 2 variables: TEMPERATURE & SIZE Higher temp = higher luminosity Bigger size = higher luminosity

25.  Apparent Magnitude – how bright a star appears to us on Earth (does not indicate actual luminosity)  Absolute Magnitude – how bright a star would appear if all stars were equal distance away

26. 1. Stars begin formation in a nebula –a cloud of gas and dust

27. 2. Protostar – gases contract, heat up (fusion has NOT started yet in the core)

28. 3. Main Sequence – hydrogen fusion has begun in the core; star is STABLE

29. 4. Red Giant - Hydrogen runs out in core, fusion stops, gravity wins - Star begins to collapse, which causes enough heat and pressure to begin helium fusion in core - Star expands and cools **Star is UNSTABLE and is dying**

30. 5. Nova – explosion of a low mass star, which leaves behind a… Planetary nebula –a cloud of gas and dust surrounding the star’s remnant core

31. White dwarf- very dense carbon-oxygen core left behind after the nova of a low mass star **The size of the Earth but the mass of the sun!

32. 1. Nebula  2. Protostar  3. Main Sequence  4. Red Supergiant  ….

35. Once the core of the red giant runs out of helium, if the temperature is high enough it can begin fusing even heavier elements. Chain of nuclear fusion: Stable stars: Hydrogen  Helium Dying stars: Helium  Carbon  Heavier Elements  Iron Iron is the heaviest element that can be fused in the core of a star.

37. 5. Super Nova – massive explosion of an unstable high mass star; source of heavy elements

38. 6a. Neutron Star (Pulsar) – EXTREMELY DENSE rapidly spinning core of a massive star left behind after a super nova explosion **measures only 10 miles across with 300,000 times the gravity of earth and about 1.5 times the mass of our Sun!

39. 6b. Black hole – final stage of an extremely massive star, with a gravitational field so intense that even light cannot escape **smaller than the City of Stafford!

40. FUSION in the cores of STARS! Teachers' Domain: The Elements: Forged in Stars (4 minute video) Teachers' Domain: The Elements: Forged in Stars (4 minute video)

41. 1. Higher star mass = faster fusion reactions = shorter life span (usually hotter & brighter) 2. Lower star mass = slower fusion reactions = longer life span (usually cooler & dimmer)

42. H-R diagram allows astronomers to determine the stage in a star’s life cycle based on where it falls on the diagram. Based on temperature and brightness. **About 90% of stars on the H-R diagram are main sequence**

43. Star Size Comparison: http://www.youtube.com/watch?v=HEheh1BH34Qhttp://www.youtube.com/watch?v=HEheh1BH34Q

45. The Electromagnetic Spectrum (light)

46. Stars emit all wavelengths; all types of electromagnetic radiation. The only type you can see is visible light! Where does this energy come from???? FUSION

47. The Electromagnetic Spectrum: Looking Through Galactic Space Clouds: http://www.youtube.com/watch?v=5GIvktBSxvw http://www.youtube.com/watch?v=5GIvktBSxvw

48. a. Wavelength represented by color b. Highest energy (shortest wavelength) = (shortest wavelength) = BLUE BLUE c. Lowest energy (longest wavelength) = (longest wavelength) = RED RED Teachers' Domain: Wavelength (quick interactive) Teachers' Domain: Wavelength (quick interactive)

49. ELEMENTS: Every element emits its own characteristic spectrum (fingerprint) 1. We can use this to determine the elements that make up the atmospheres of stars and planets!

50. MOTION: Can determine the speed & direction of moving celestial objects Doppler effect – apparent change in wavelength of radiation or sound that indicates whether an object is moving towards or away Understanding the Doppler Effect: http://www.youtube.com/watch?v =WCEhidp8tiA http://www.youtube.com/watch?v =WCEhidp8tiA

51. Red shift - wavelength stretches as objects move away from each other, shifting the visible spectrum to the red end Blue Shift - wavelength shortens as objects move toward each other, shifting to the visible spectrum to the blue end

52.  Formation of the Solar System: http://www.youtube.com/watch?v=Uhy1fucSRQI Formation of the Solar System: http://www.youtube.com/watch?v=Uhy1fucSRQI

53.  A large gas cloud ( nebula ) contracted through gravity  The sun formed in the center  ‘Seeds’ of matter began to clump together in a disk, and their gravity attracted more matter, eventually forming planets  Solar wind blew the remaining dust away.