1. Electromagnetic Spectrum Lecture

2. Standards Explain how objects in the universe emit different electromagnetic radiation and how this information is usedExplain how objects in the universe emit different electromagnetic radiation and how this information is used Examine the role that NM research facilities play in current space exploration (e.g., Very Large Array)Examine the role that NM research facilities play in current space exploration (e.g., Very Large Array) Understand how knowledge about the universe comes from evidence collected from advanced technology (e.g., telescopes)Understand how knowledge about the universe comes from evidence collected from advanced technology (e.g., telescopes) Describe wave propagation using amplitude, wavelength and frequencyDescribe wave propagation using amplitude, wavelength and frequency

3. Electromagnetic Radiation Electromagnetic Radiation -Electromagnetic Radiation - another term for light. energy informationIt transfers energy and information from one place to another.

4. Electromagnetic Spectrum The range of electromagnetic radiation: radio waves, infrared, visible, ultraviolet, x-rays and gamma rays.The range of electromagnetic radiation: radio waves, infrared, visible, ultraviolet, x-rays and gamma rays. These all differ in wavelengthThese all differ in wavelength They all travel the same speed in a vacuum: 300,000 km/s or 186,000 mi/s. This is the speed of light, denoted by c.They all travel the same speed in a vacuum: 300,000 km/s or 186,000 mi/s. This is the speed of light, denoted by c. Snap your fingersSnap your fingers In the time it takes you to snap your fingers, light travels ¾ of the way around the earth.In the time it takes you to snap your fingers, light travels ¾ of the way around the earth.

5. The Electromagnetic Spectrum

7. Electromagnetic Spectrum Radiation is the way in which energy is transmitted through space from one point to another without the need for any physical connection between the two locations.Radiation is the way in which energy is transmitted through space from one point to another without the need for any physical connection between the two locations. Electromagnetic means that the energy is carried in the form of rapidly fluctuating electric and magnetic fields.Electromagnetic means that the energy is carried in the form of rapidly fluctuating electric and magnetic fields.

8. Electric & Magnetic Wave Fields

9. Electromagnetic Spectrum Visible light is the wavelength that human eyes are sensitive toVisible light is the wavelength that human eyes are sensitive to We experience sight when:We experience sight when: 1.Light enters the eye 2.The cornea and lens focus it onto the retina 3.An electrical impulse goes to the brain, giving us the sensation of sight

10. Wave Motion All electromagnetic radiation travels through space in the form of waves.All electromagnetic radiation travels through space in the form of waves. Energy is transferred from one place to another without the movement of the material it’s traveling through.Energy is transferred from one place to another without the movement of the material it’s traveling through. Waves do not need a medium (i.e., substance) to travel through.Waves do not need a medium (i.e., substance) to travel through.

11. Wave Motion Draw the following wave and label its partsDraw the following wave and label its parts This is a transverse waveThis is a transverse wave Crest Trough Wavelength Resting point Frequency Frequency = # waves second Amplitude

12. Wave Motion Wavelength is measured in units of Ångstroms (Å) (older unit) or nanometers (nm)Wavelength is measured in units of Ångstroms (Å) (older unit) or nanometers (nm) There are 10 9 nm in 1 meter:There are 10 9 nm in 1 meter: 10 9 = 1,000,000,00010 9 = 1,000,000,000

13. Wave Motion Visible wavelengths range from 400 – 700 nm or 4000 – 7000 Å.Visible wavelengths range from 400 – 700 nm or 4000 – 7000 Å. Your eyes are most sensitive to the 550 nm, or 5500 Å wavelength.Your eyes are most sensitive to the 550 nm, or 5500 Å wavelength. This is yellow-green: the newer color of fire trucks and school crossing signs.This is yellow-green: the newer color of fire trucks and school crossing signs. The sun emits most of its energy in this wavelength.The sun emits most of its energy in this wavelength.

14. Parts of the Electromagnetic Spectrum RadioRadio InfraredInfrared VisibleVisible UltravioletUltraviolet X-raysX-rays Gamma raysGamma rays

15. Radio Waves Longest wavelengths, therefore lowest energyLongest wavelengths, therefore lowest energy 1 cm to 10 8 m 1 cm to 10 8 m Includes radar, microwave, AM, FM and TVIncludes radar, microwave, AM, FM and TV

16. Radio Waves Radio telescopes collect and concentrate radio wavesRadio telescopes collect and concentrate radio waves They are giant antennasThey are giant antennas Radio waves were discovered in 1930Radio waves were discovered in 1930 By 1940, the radio sky was chartedBy 1940, the radio sky was charted Technology was developed because of WWIITechnology was developed because of WWII

17. Radio Waves Radio telescopes can observe 24 hours a dayRadio telescopes can observe 24 hours a day Can observe parts of the universe that can’t be seen opticallyCan observe parts of the universe that can’t be seen optically Ex: black holes. Never observed before radio astronomy Ex: black holes. Never observed before radio astronomy

18. SgrA: black hole at center of Milky Way Photo: UC Berkely, http://www.berkeley.edu/news/media/releases/2002/10/23_bhole.html

19. Radio Waves Radio telescopes have poor angular resolutionRadio telescopes have poor angular resolution Resolution = the ability to distinguish between objects that are close together. Resolution = the ability to distinguish between objects that are close together. Higher resolution = better detail. Higher resolution = better detail. Interferometry –technique where two or more telescopes are put together to increase resolution.Interferometry –technique where two or more telescopes are put together to increase resolution. They look at the same object, in the same wavelength, at the same time They look at the same object, in the same wavelength, at the same time

20. Radio Telescopes VLA = Very Large ArrayVLA = Very Large Array Radio telescopes located on San Agustin Plains near Socorro, NM Radio telescopes located on San Agustin Plains near Socorro, NM Located at 7000 ft and isolated in mountain ranges to block interference from other radio sources. Located at 7000 ft and isolated in mountain ranges to block interference from other radio sources. World renowned astronomers come here from all over the world. World renowned astronomers come here from all over the world.

21. Radio Telescopes 28 antennas (27 working, one for replacing during repairs) 28 antennas (27 working, one for replacing during repairs) Arranged in a Y-shaped configuration Arranged in a Y-shaped configuration Each telescope is 25 meters in diameter (about length of classroom) and weighs 235 tons Each telescope is 25 meters in diameter (about length of classroom) and weighs 235 tons Receivers are cooled to -430  F to get rid of interference. Receivers are cooled to -430  F to get rid of interference.

22. VLA Y-Shaped Configuration Photo: http://bigbro.biophys.cornell.edu/~toombes/Science_Education/ Crystal_Radio/VLA.jpg

23. Photos: L. Brown, June 2007

24. Photo: L. Brown, June 2007

26. Photo: NROA, http://www.cv.nrao.edu/ ~abridle/images.html VLA Under Radio Sky

27. Radio Telescopes National Radio Astronomy Observatory, Green Bank, West VirginiaNational Radio Astronomy Observatory, Green Bank, West Virginia World’s largest moveable radio telescope World’s largest moveable radio telescope 43 m in diameter & 150 m tall (taller than Statue of Liberty) 43 m in diameter & 150 m tall (taller than Statue of Liberty) Original structure collapsed, has been rebuilt Original structure collapsed, has been rebuilt

28. Photo: APOD, http://antwrp.gsfc.nasa.gov/apod/ap020311.html

29. Radio Telescopes Arecibo Observatory, Puerto RicoArecibo Observatory, Puerto Rico World’s largest radio telescope World’s largest radio telescope 300 m in diameter 300 m in diameter Surface spans nearly 20 acres Surface spans nearly 20 acres

30. Photo: http://www.evlbi.org/evlbi/te024/te024.html

31. Photo: http://commons.wikimedia.org/wiki/Image:Arecibo_Observatory_Aerial.jpg

32. Radio Telescopes Very Long Baseline ArrayVery Long Baseline Array 10 radio telescopes spanning 5,351 miles 10 radio telescopes spanning 5,351 miles World’s largest and sharpest (you could be in Los Angeles and clearly read a street sign in New York City World’s largest and sharpest (you could be in Los Angeles and clearly read a street sign in New York City Used to observe quasars, black holes and stars in every stage of stellar life cycle Used to observe quasars, black holes and stars in every stage of stellar life cycle

33. Very Long Baseline Array

34. Radio Telescopes Atacama Large Millimeter/submillimeter Array (ALMA) (still being built)Atacama Large Millimeter/submillimeter Array (ALMA) (still being built) Highest array at 16,500’ Highest array at 16,500’ In Atacama desert, Chile In Atacama desert, Chile At least 66 telescopes At least 66 telescopes Maximum range = 71,000 square feet of radio light collecting area Maximum range = 71,000 square feet of radio light collecting area Largest leap in telescope technology since Galileo first aimed a lens on the universe Largest leap in telescope technology since Galileo first aimed a lens on the universe

35. ALMA

36. Infrared (IR) Wavelengths are just longer than we can see without special gogglesWavelengths are just longer than we can see without special goggles Infrared radiation is heat (produced by many objects)Infrared radiation is heat (produced by many objects) It is used in the medical field, police work, military…(night vision goggles)It is used in the medical field, police work, military…(night vision goggles)

37. Infrared (IR) Infrared telescopes are placed in high, dry areas because Earth’s atmosphere interferes with IR radiationInfrared telescopes are placed in high, dry areas because Earth’s atmosphere interferes with IR radiation Telescopes need to be cooled down close to absolute zeroTelescopes need to be cooled down close to absolute zero Equipped with a bolometer, made of germanium, to detect the IREquipped with a bolometer, made of germanium, to detect the IR Bolometer = device used to measure electromagnetic radiationBolometer = device used to measure electromagnetic radiation

38. Infrared (IR) Infrared telescopes can see through interstellar dustInfrared telescopes can see through interstellar dust Ex: can see the center of Milky Way Ex: can see the center of Milky Way Can be used during the dayCan be used during the day

39. Center of Milky Way: Spitzer

40. Orion Nebula in IR & Visible

41. Infrared (IR) IR observatories in space (above Earth’s atmosphere):IR observatories in space (above Earth’s atmosphere): Spitzer Space Telescope – current IR telescope, launched in 2003 Spitzer Space Telescope – current IR telescope, launched in 2003

42. Spitzer and Milky Way Photo: NASA, http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=1546

43. Visible Light White light is made up of the colors red, orange, yellow, green, blue, indigo, violet.White light is made up of the colors red, orange, yellow, green, blue, indigo, violet. Remember the acronym ROY G BIVRemember the acronym ROY G BIV 400 -700 nm wavelengths400 -700 nm wavelengths Sir Isaac Newton discovered this 300 years agoSir Isaac Newton discovered this 300 years ago The color is determined by the wavelength:The color is determined by the wavelength: Red has the longest wavelength Red has the longest wavelength Violet has the shortest wavelength Violet has the shortest wavelength Observing in visible light is called optical astronomyObserving in visible light is called optical astronomy

44. Ultraviolet (UV) Wavelengths 400 nm down to a few nanometersWavelengths 400 nm down to a few nanometers Causes sunburn and cancerCauses sunburn and cancer Helps produce vitamin DHelps produce vitamin D Ozone protects Earth from most UV radiation, so UV studies must be done above Earth’s atmosphereOzone protects Earth from most UV radiation, so UV studies must be done above Earth’s atmosphere

45. Ultraviolet (UV) UV telescopes:UV telescopes: Far Ultraviolet Explorer (FUSE) – launched in 1999 Far Ultraviolet Explorer (FUSE) – launched in 1999 Galaxy Evolution Explorer (GALEX) – launched in 2003 Galaxy Evolution Explorer (GALEX) – launched in 2003 Hubble Space Telescope has UV detectors Hubble Space Telescope has UV detectors

46. X-Rays Wavelengths are a few nm to hundredths of a nmWavelengths are a few nm to hundredths of a nm Have medical usesHave medical uses Blocked by Earth’s atmosphere, so observing done from spaceBlocked by Earth’s atmosphere, so observing done from space

47. X-Rays X-Ray telescopes:X-Ray telescopes: Chandra X-Ray Observatory – launched in 1999 aboard the Columbia. Still in operation Chandra X-Ray Observatory – launched in 1999 aboard the Columbia. Still in operation Nustar X-Ray Telescope – launched June 13, 2012 to image the sky in high energy x-rays Nustar X-Ray Telescope – launched June 13, 2012 to image the sky in high energy x-rays

48. Chandra

49. W49b: Supernova: Chandra

50. Nustar

51. Gamma Rays Shortest wavelength, therefore highest energyShortest wavelength, therefore highest energy Associated with radioactivityAssociated with radioactivity Observing done from spaceObserving done from space

52. Gamma Rays Telescopes count photons in a given directionTelescopes count photons in a given direction Photon – packet of electromagnetic radiation (i.e., particle of light) Photon – packet of electromagnetic radiation (i.e., particle of light) Photons are scarce, takes hours to days to capture one photon Photons are scarce, takes hours to days to capture one photon Fermi Space Telescope – launched June 11, 2008Fermi Space Telescope – launched June 11, 2008

53. Artists illustration of Fermi Space Telescope Photo: http://www.msnbc.msn.com/id/ 26408952/

54. Moon in Gamma: CGRO Photo: http://www.answers.com/topic/ gamma-ray?cat=health

55. The Sky in Many Wavelengths Slide Show

56. Milky Way in Visible Light Photo: University of Washington, http://www.astro.washington.edu/labs/clearinghouse/ lecture/pix.html

57. Milky Way in Radio: 73 cm wavelength Photo: Washington University,http://www.astro.washington.edu/labs/clearinghouse/ lecture/pix.html

58. Milky Way in Radio: 21 cm wavelength Photo: Washington University,http://www.astro.washington.edu/labs/clearinghouse/ lecture/pix.html

59. Milky Way in Microwaves: COBE

60. Galactic Center in Radio Photo: UC San Diego, http://cassfos02.ucsd.edu/public/tutorial/images/gc_1meter.jpg

61. Milky Way in IR: IRAS Photo: Caltech, http://www.ipac.caltech.edu/Outreach/Gallery/IRAS/IRAS_allsky_big.jpg

62. Photo: http://www. astro.livjm.ac.uk/ courses/phys134/ cosmo.html

63. Sky in Ultraviolet Photo: http://minho.kasi.re.kr/iCAP/ ImageGallery/0705.AllSky.html

64. X-Ray Sky: ROSAT Photo: APOD, http://zuserver2.star.ucl.ac.uk/~apod/apod/ap961008.html

65. Gamma Ray Sky Photo: http://www.mpi-hd.mpg.de/hfm/ HESS/public/physics/allsky1_egret.gif

66. 1 st Light for Fermi Gamma Ray Telescope, 8-26-08

67. Milky Way in Multiple Wavelengths