Ch 22 The Sun & It’s Solar System

1. Ch 22 The Sun & It’s Solar System http://www.brainpop.com/science/space/sun/index.weml

2. I. Safe Methods for Studying the Sun • Spectroscope • Solar Telescope • Satellites

3. 1. Spectroscope • Chemical composition • Temperature • Internal Pressure

4. 2. Solar Telescopes • Projects a large image of the sun into a dark underground room • Uses special glasses for viewing • Ex. Kitt Peak National Observatory in AZ

5. 3. Satellites • SOHO (Solar and Heliospheric Observatory): Study Sun-Earth Connection, launched in 1996 • YOHKOH Spacecraft (designed to study the Sun’s Corona, launched in 1991): • ULYSSES in a polar orbit over the sun

6. Solar Max to Solar Minimum

7. B. Properties of the Sun • Average size star • Diameter = 1,380,000 Km • Surface Temp = 55000C • Interior Temp = 15,000,0000C

8. C. The Sun’s Atmosphere • 3 Regions • Photosphere • Chromosphere • Corona

9. 1. Photosphere • Apparent bright yellow surface of the sun • Area of Sunspots • Made of Granules • Granules- the tops of individual columns of gases • Gases rise from region below the photosphere

10. 2. Chromosphere • Above Photosphere • Lower part of the outer atmosphere • Seen only during a solar eclipse • Colored Red by glowing Hydrogen • Radiates mostly X-rays & UV • Area of prominences

11. 3. Corona • Above Chromosphere • So sparse in gas it would be considered a vacuum on Earth • Seen during a total solar eclipse as a faint, pearly light

12. D. Solar Features • Sunspots- Dark, cooler areas on the photosphere that occur in cycles • Dark center called an umbra • Lighter rim called penumbra • Occur in pairs of opposite magnetic charge, like a bar magnet • Appear to move from left to right across the photosphere

13. 2. Solar Prominences • Huge loops of gas that connect different parts of sunspot regions

14. 3. Solar Flares • Sudden eruption of heatedhydrogen & energy around the area of a sunspot (a prominence that has exploded) • Directly correlated to sunspot # (#of sunspots ,# of solar flares) • Source of Solar wind bursts • http://www.trschools.com/staff/g/cgirtain/flare1.mpg

15. 4. Solar Wind • Constant stream of electrically charged particles coming from the corona • Given off in all directions

16. 5. Coronal Holes • Great tears in the Corona • May extend halfway around the sun • Do not close for several months • Source of solar winds

17. 6.Auroras • Northern Lights = Aurora Borealis • Particles of solar winds interacting with Earth's Magnetic Field & upper atmosphere • Mostly occur in Earth's polar regions

18. 7. Magnetic Storms • When particles thrown out by coronal holes & solar flares are added to the constant solar winds • Auroras may be seen at middle latitudes • Compasses may read incorrectly • Cellular & cordless telephone reception may be interrupted • May interfere with radio frequencies

19. Sun Spots to Auroras

20. E. Source of the Sun’s Energy • E=mc2 • Matter can be converted to energy & vice versa • Fusion Reactions: Hydrogen that doesn’t become Helium becomes Energy • 5 Billion years of fuel left in the sun • Core is only place on sun where temp, density & pressure are all great enough to sustain nuclear fusion.

21. II. Observing the Solar System • Solar System includes:1. 8 Planets2. Many Natural Satellites (moons)3. Asteroids, Meteoroids, Comets

22. Solar System Cont’ • All of the planets travel in elliptical orbits (paths around the sun) • 5 planets can be seen without a telescope • Mercury • Venus • Mars • Jupiter • Saturn • Meteors can also be seen

28. B. Planets & Stars • Position of planets related to constellations changes constantly • Planets move through the Ecliptic (path through the Zodiac Constellations) • Most planets move eastward, night after night through the sky

29. Retrograde Motion

30. C. Retrograde motion • Apparent westward loop of a planet in its path across the sky • Occurs because each planet travels around the sun at different speeds • Planet appears to move backward when the Earth overtakes it. • The more distant the planet is the slower it changes

31. D. Solar System Models 1. Heliocentric Sun centered model of solar system • Present day model • Developed by Copernicus (1473-1543)

32. 2. Geocentric Earth centered system • Developed by Ptolemy 140 AD a. epicycles- small orbit of a planet b. deferent- large orbit of planets around the Earth

33. III. Motions in the Solar System • Tycho Brahe (1546-1601) • 1st Long Term Sky Observations (20 years worth) • Supported geocentric model • Believed Sun & Moon revolved around Earth • Thought other planets revolve around sun • Several versions, some have Earth rotating • Recognition of failure of Ptolemy's model

34. B. Johannes Kepler • Inherited Tycho's work • Supported Heliocentric Model  • Designed 3 Laws of Planetary Motion

35. 3 Laws of Planetary Motion • 1st Law - Planets travel in elliptical orbits with the sun as the focus      a. Aphelion - pt. in planet's orbit where it is furthest from the sun      b. Perihelion - pt. in planet's orbit nearest the sun   

36. 2nd Law Equal Area Law • Speed of a planet around the sun is not constant • Planets travel more rapidly when closer to the sun http://home.cvc.org/science/kepler.htm http://www.sciencejoywagon.com/physicszone/lesson/03circ/keplers.htm

37. 3rd Law is the Harmonic Law • The time it takes a planet to travel one orbit around the sun = its period • P2=D3 • P is the period measured in years & D is distance in AU (astronomical units) • The further a planet is from the sun, the longer its revolution

38. C. Galileo • 1st Astronomer with a telescope • Drew craters he observed on the  surface of the moon • Discovered 4 largest moons of Jupiter • His findings supported the heliocentric model of the solar system   

39. D. Sir Isaac Newton • Universal Law of Gravitation:Change in Force =  1                             d2 • Gravity & Distance are inversely correlated • Gravity & Mass are directly correlated

40. Newton’s Work • Force of gravity between any 2 objects is related to the distance between the objects & the masses of the two objects • Calculated the mass of planets from dimensions of orbit • Thought tides were caused by force of moon as it revolves around Earth • Used gravity to explain the long orbit of comets & proved they are a part of the solar system

41. VI. Other Objects in the Solar System • Asteroids - large piece of rock in space; largest is Ceres, then Pallas • Escape Velocity- minimum velocity needed to escape the gravitational pull of a planet, moon, or asteroid http://www.spaceweather.com/ Scroll down for near Earth misses

42. ASTEROID FLYBY • On March 3rd,2003 a 25-meter wide asteroid, 2003 DW10, flew past Earth only 1.4 times farther from our planet than the Moon. John Rogers of the Camarillo Observatory captured this image of the 17th magnitude space rock on March 2nd. Rogers tracked the asteroid, not the stars, so 2003 DW10 appears as a point-like speck in the middle of the image. The surrounding stars are streaked. [3D orbit] [ephemeris]

43. C. Kuiper Belt • Vast disk of icy comets starting near Neptune’s orbit

44. D. Comets- • Composed of dust & rock particles mixed in with frozen water, methane & ammonia; most have very eccentric orbits

45. Comet Hyakutake: Photograph by M.Geyser.

46. Parts of a comet: • Coma - hazy, melting ice cloud around the solid part of the comet • Nucleus - solid ball of the comet • Tail - formed by the solar winds pushing away small melting particles; always faces away from the sun • Ex. Halley’s, Encke’s, & Hale-Bopp 

47. Comets

48. E. Meteoroids • - The small pieces of rock moving from space; possibly left over from a fully melted comet F. Meteor - a meteoroid that burns up in Earth’s atmosphere; glows as it is falling

49. G. Meteorite - • The part of a meteoroid that did not totally burn up & strikes the Earth, sometimes making a crater (Barringer Crater Az 25,000 yrs ago) • Antarctic ice caps have the most meteorites • Meteor craters are common on moons & some planets, but not on Earth because:1. atmosphere burns Meteors up2. Earth is geologically active & weathering occurs; erases some of the marks