1. Astronomy 101 The Solar System Tuesday, Thursday 2:30-3:45 pm Hasbrouck 20 Tom Burbine tomburbine@astro.umass.edu

2. Course Course Website: –http://blogs.umass.edu/astron101-tburbine/http://blogs.umass.edu/astron101-tburbine/ Textbook: –Pathways to Astronomy (2nd Edition) by Stephen Schneider and Thomas Arny. You also will need a calculator.

3. Office Hours Mine Tuesday, Thursday - 1:15-2:15pm Lederle Graduate Research Tower C 632 Neil Tuesday, Thursday - 11 am-noon Lederle Graduate Research Tower B 619-O

4. Homework We will use Spark https://spark.oit.umass.edu/webct/logonDisplay.d owebcthttps://spark.oit.umass.edu/webct/logonDisplay.d owebct Homework will be due approximately twice a week

5. Astronomy Information Astronomy Help Desk Mon-Thurs 7-9pm Hasbrouck 205 The Observatory should be open on clear Thursdays Students should check the observatory website at: http://www.astro.umass.edu/~orchardhill for updated information http://www.astro.umass.edu/~orchardhill There's a map to the observatory on the website.

6. Final Monday - 12/14 4:00 pm Hasbrouck 20

7. No class this Tuesday Space Station Bound: A Day in the Life of a Scientist Astronaut with Cady Coleman '91PhD Tuesday, October 13, 2009 4:00 pm Engineering Lab II Room 119 Free Admission

8. HW #5 (replace) Due Today

9. HW #7 Due next Thursday

10. HW #8 Due next Thursday

11. October 9 (Tomorrow): 7:30 AM LCROSS (Lunar Crater Observation and Sensing Satellite) LCROSS’ spent Upper-Stage Centaur Rocket will crash into the Moon;s South Pole LCROSS will then follow into the Moon Looking for water http://www.youtube.com/watch?v=NQ8d2Oacv2M

12. New Rings around Saturn Seen in the infrared by the Spitzer Telescope Made of dust and ice; Dust is 80 Kelvin Lies some 13 million km from the planet Tilted 27 degrees from main ring plane 50 times more distant than the other rings and in a different plane. Probably made up of debris kicked off Saturn's moon Phoebe by small impacts.

13. Why infrared for dust? Cold things give off more light in infrared than visible

14. Blackbody A black body is an object that absorbs all electromagnetic radiation that falls onto it. Perfect emitter of radiation Radiates energy at every wavelength http://www.daviddarling.info/images/blackbody.jpg

15. Stefan-Boltzman Law - energy radiated per unit surface area of a black body in unit time is directly proportional to the fourth power of the black body’s temperature Wien’s Law - blackbody curve at any temperature has essentially the same shape as the curve at any other temperature, except that each wavelength is displaced, or moved over, on the graph

16. Stars and planets act can be modeled as blackbodies http://www.astro.ncu.edu.tw/contents/faculty/wp_chen/Ast101/blackbody_curves.jpg

17. Blackbody curves http://www.mhhe.com/physsci/astronomy/applets/ Blackbody/frame.htmlhttp://www.mhhe.com/physsci/astronomy/applets/ Blackbody/frame.html

18. http://www.rap.ucar.edu/general/asap-2005/Thur-AM2/Williams_DoD_Satellites_files/slide0005_image020.gif

19. Power Power is in Joules/second = Watts

20. Stefan-Boltzman Law Emitted power per square meter of surface = σT 4 Temperature in Kelvin σ = 5.7 x 10 -8 Watt/(m 2 * K 4 ) For example, if the temperature of an object is 10,000 K Emitted power per square meter = 5.7 x 10 -8 x (10,000) 4 Emitted power per square meter = 5.7 x 10 -8 x (1 x 10 16 ) Emitted power per square meter = 5.7 x 10 8 W/m 2

21. Wien’s Law Wavelength of Maximum intensity of the blackbody curve peak = 2,900,000 nm T (Kelvin) λ max = 2,900,000/10,000 nm λ max = 290 nm 1 nanometer = 1 x 10 -9 meters λ max = 290 nm = 2.0 x 10 -7 meters

23. When you observe an astronomical body You measure intensity Intensity – amount of radiation

24. When you see an object in the sky You measure its brightness Its brightness is a function of its –Distance from Earth (can be calculated from orbit) If star: -Luminosity - is the amount of energy a body radiates per unit time If planet –Albedo –Size

26. Inverse Square Law The apparent brightness varies inversely by the square of the distance (1/d 2 ) If the Earth was moved to 10 Astronomical Units away, the Sun would be 1/100 times dimmer If the Earth was moved to 100 Astronomical Units away, the Sun would be 1/10000 times dimmer

27. If the Earth was moved to 1 x 10 8 Astronomical Units away, the Sun would be … A) 1 x 10 -12 times dimmer B) 1 x 10 -14 times dimmer C) 1 x 10 -16 times dimmer D) 1 x 10 -18 times dimmer E) 1 x 10 -20 times dimmer

28. If the Earth was moved to 1 x 10 8 Astronomical Units away, the Sun would be … A) 1 x 10 -12 times dimmer B) 1 x 10 -14 times dimmer C) 1 x 10 -16 times dimmer D) 1 x 10 -18 times dimmer E) 1 x 10 -20 times dimmer

29. Luminosity-Distance Formula Apparent brightness = Luminosity 4  x (distance) 2 Usually use units of Solar Luminosity L Sun = 3.8 x 10 26 Watts

32. Magnitude System Brighter –lower number http://www.astronomynotes.com/starprop/appmag.gif 4 Vesta brightest asteroid

33. Magnitude differenceRelative intensity 01 12.51 26.31 315.8 439.8 5100 1010 4 1510 6

35. Initially Everybody observed with their eyes

36. Figure 7.1

37. Figure 7.2a Parallel lightLens

38. Figure 7.2b

39. Why are Telescopes better than your eyes? They can observe light in different wavelength regions (eyes can only see visible light) They can collect more light than eyes They can be built to compensate for the distorting effects of the atmosphere

40. Figure 7.6 Refracting telescope

41. Reflecting Telescope

42. Reflecting Telescopes

43. Resulting image inverted

44. All large modern telescopes are reflectors Since light passes through the lens of a refracting telescope, You need to make the lens from clear, high- quality glass with precisely shaped surfaces

45. It is Its easier to make a high-quality mirror than a lens

46. Also, Large lenses are extremely heavy

47. Also Lens focuses red and blue light slightly differently Called chromatic aberration http://en.wikipedia.org/wiki/File:Lens6a.svg

48. Also Light can be absorbed by the glass as it passes through the glass Minor problem for visible, but severe for ultraviolet and infrared light

49. Size of a telescope Diameter of its primary mirror or lens Light collecting area is proportional to the diameter squared since Collecting area =  r 2 E.g., 8-meter telescope

50. Telescope that took image b is twice as big as telescope that took image a Larger the telescope, more detail can be seen ab

51. Telescope on Mauna Kea (14,000 feet high) Telescope is Japanese Subaru 8-m telescope

52. Atmosphere Atmosphere can absorb light Atmosphere can scatter light Atmosphere can distort light (twinkling)

53. Twinkling Twinkling of stars is caused by moving air currents in the atmosphere. The beam of light from a star passes through many regions of moving air while on its way to an observer’s eye or telescope. Each atmospheric region distorts the light slightly for a fraction of a second.

55. Advantages of space-based telescopes It can be open 24 hours, 7 days of week Do not have to worry about distorting effects of atmosphere There is no extra background of light due to scattering of light in the Earth’s atmosphere Observe in more wavelength regions

56. Figure 7.20

57. http://www.scienzagiovane.unibo.it/English/radio-window/images/radiazioni-em.jpg

58. Infrared light absorbed by molecules http://www.ucar.edu/learn/1_3_1.htm

59. Not all light from a star reaches Earth

60. Light in space can be affected by dust http://www.ipac.caltech.edu/2mass/outreach/survey.html http://en.wikipedia.org/wiki/File:Rayleigh_sunlight_scattering.png

62. It does not help That you are closer to the stars

63. To measure light In the past, they used photographic plates Now they use CCDs (charge-coupled devices) CCD are electronic detectors CCDs are chips of silicons

64. Figure 7.5

65. CCDs CCDs convert light into electrons William Boyle George Smith Shared the 2009 Physics Nobel Prize for their discovery

66. How do they work? The CCD is made up of pixels. As the light falls on each pixel, the photons become electrons due to the photoelectric effect. The photoelectric effect happens when photons of light hit the silicon of the pixel and knock electrons out of place. These electrons are then stored. Essentially, the charge in each row is moved from one site to the next, a step at a time. This has been likened to a “bucket row” or human chain, passing buckets of water down a line. As these buckets of electrons reach the end of the line they are dumped out and measured, and this analog measurement is then turned into a digital value. Thus, a digital grid is made which describes the image.

67. Color separation for digital cameras Colored filters

68. CCDs CCDs can collect 90% of photons that strike them Photographic plates can only collect 10% of the photons CCDs are split into squares called pixels Data is in electronic form

69. Hubble Telescope Can observe in visible, infrared, and ultraviolet wavelength regions Named after Edwin Hubble, the father of modern cosmology

70. Hubble (launched in 1990) Telescope is the size of a school bus 2.4 m mirror

72. Initially Hubble’s primary mirror was polished to the wrong shape Was too flat at the edges Was barely 2.3 micrometers out from the required shape (1/50 the width of a human hair) Images were not focused as well as they could be Later shuttle mission fixed this problem by installing a number of small mirrors

73. http://dayton.hq.nasa.gov/IMAGES/SMALL/GPN-2002-000064.jpg

74. Jupiter

75. http://video.nationalgeographic.com/video/player/ science/space-sci/exploration/hubble-sci.htmlhttp://video.nationalgeographic.com/video/player/ science/space-sci/exploration/hubble-sci.html

76. Hubble replacement The first major components of the new James Webb Space Telescope are now being assembled. While Hubble is the size of a bus, the new James Webb will be the size of a jetliner. Will launch in 2014 James Webb is a former NASA administrator during the Apollo program

77. http://www.youtube.com/watch?v=SpkrVw_E6N w

78. Any Questions?