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No-Name Clickers. 4D8AC7641AFE8 A9EDE4ADE3856B DEAEB0CE019A95 E103D23E1C0E1C EEB8560161E040C 1E0AF2E6 2304FED9 23210E0C 246EB0FA 24A429A9 24DAC53B 24E06FAB 25A321A7. Chapter 3 Telescopes. Telescopes. Optical Telescopes. - PowerPoint PPT Presentation

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No-Name Clickers4D8AC7641AFE8A9EDE4ADE3856BDEAEB0CE019A95E103D23E1C0E1CEEB8560161E040C1E0AF2E62304FED923210E0C246EB0FA24A429A924DAC53B24E06FAB25A321A7Copyright 2010 Pearson Education, Inc.Chapter 3 TelescopesCopyright 2010 Pearson Education, Inc.

Copyright 2010 Pearson Education, Inc.

TelescopesCopyright 2010 Pearson Education, Inc.3Chapter 3Optical TelescopesTelescope SizeHigh-Resolution AstronomyRadio AstronomyOther AstronomiesCopyright 2010 Pearson Education, Inc.4Images can be formed through reflection or refraction.Reflecting mirrorOptical Telescopes

Collect a large amount of lightCopyright 2010 Pearson Education, Inc.5Refracting lensOptical Telescopes

Copyright 2010 Pearson Education, Inc.6

Optical TelescopesImage formationCopyright 2010 Pearson Education, Inc.7Reflecting and refracting telescopesOptical Telescopes

Copyright 2010 Pearson Education, Inc.8Modern telescopes are all reflectors: Light traveling through lens is refracted differently depending on wavelength. Some light traveling through lens is absorbed. Large lens can be very heavy, and can only be supported at edge. Lens needs two optically acceptable surfaces, mirror only needs one.Optical TelescopesCopyright 2010 Pearson Education, Inc.9

Chromatic aberrationCopyright 2010 Pearson Education, Inc.Types of reflecting telescopesOptical Telescopes

Copyright 2010 Pearson Education, Inc.11Question 1Modern telescopes use mirrors rather than lenses for all of these reasons EXCEPTa) light passing through lenses can be absorbed or scattered.b) large lenses can be very heavy.c) large lenses are more difficult to make.d) mirrors can be computer controlled to improve resolution.e) reflecting telescopes arent affected by the atmosphere as much.

12Answer: eQuestion 1Modern telescopes use mirrors rather than lenses for all of these reasons EXCEPTa) light passing through lenses can be absorbed or scattered.b) large lenses can be very heavy.c) large lenses are more difficult to make.d) mirrors can be computer controlled to improve resolution.e) reflecting telescopes arent affected by the atmosphere as much.Reflecting instruments like the KECK telescopes can be made larger, and more capable, than refractors.

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Optical TelescopesDetails of the Keck telescope

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Image acquisition: Charge-coupled devices (CCDs) are electronic devices, can be quickly read out and reset.Optical TelescopesCopyright 2010 Pearson Education, Inc.15

CCD Camera SensorCopyright 2010 Pearson Education, Inc.a) they dont require chemical development.b) digital data is easily stored & transmitted.c) CCDs are more light sensitive than film.d) CCD images can be developed faster.e) All of the above are true.An advantage of CCDs over photographic film isQuestion 2

17Answer: ea) they dont require chemical development.b) digital data is easily stored & transmitted.c) CCDs are more light sensitive than film.d) CCD images can be developed faster.e) All of the above are true.An advantage of CCDs over photographic film isQuestion 2

18Image processing by computers can sharpen images.Optical Telescopes

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Ground Based TelescopeCopyright 2010 Pearson Education, Inc.

Early HSTCopyright 2010 Pearson Education, Inc.

Computer Enhanced HSTCopyright 2010 Pearson Education, Inc.

Later HST

Copyright 2010 Pearson Education, Inc.The Hubble Space Telescope has several instruments.

The Hubble Space TelescopeCopyright 2010 Pearson Education, Inc.24

Resolution achievable by the Hubble Space Telescope limited by optics and not atmosphereThe Hubble Space TelescopeGround Based M100Copyright 2010 Pearson Education, Inc.25

Copyright 2010 Pearson Education, Inc.Light-gathering power:Improves detailBrightness proportional to square of radius of mirrorThe figure, part (b) was taken with a telescope twice the size of (a)Telescope Size

Area = p R2R=1R=2Copyright 2010 Pearson Education, Inc.27Multiple telescopes: Mauna KeaTelescope Size

Copyright 2010 Pearson Education, Inc.28Telescope SizeThe VLT (Very Large Telescope), Atacama, Chile

Copyright 2010 Pearson Education, Inc.29a) bend around corners and edges.b) separate into its component colors.c) bend through a lens.d) disperse within a prism.e) reflect off a mirror.Diffraction is the tendency of light to Question 3

30Answer: aa) bend around corners and edges.b) separate into its component colors.c) bend through a lens.d) disperse within a prism.e) reflect off a mirror.Diffraction is the tendency of light to Question 3Diffraction affects all telescopes and limits the sharpness of all images.

31Resolving power: Ability to distinguish objects that are close together.Resolution is proportional to wavelength and inversely proportional to telescope size.Telescope Size

Copyright 2010 Pearson Education, Inc.32Question 4Resolution is improved by usinga) larger telescopes & longer wavelengths. b) infrared light.c) larger telescopes & shorter wavelengths. d) lower frequency light.e) visible light.

33Answer: cQuestion 4Resolution is improved by usinga) larger telescopes & longer wavelengths. b) infrared light.c) larger telescopes & shorter wavelengths. d) lower frequency light.e) visible light.Diffraction limits resolution; larger telescopes and shorter-wave light produces sharper images.

10134Effect of improving resolution:(a) 10; (b) 1; (c) 5; (d) 1Telescope Size

Copyright 2010 Pearson Education, Inc.35a) the quality of the telescopes optics.b) the transparency of a telescopes lens.c) the sharpness of vision of your eyes.d) the image quality due to air stability.e) the skys clarity & absence of clouds.Seeing in astronomy is a measurement ofQuestion 5

36Answer: dSeeing in astronomy is a measurement ofQuestion 5Good Seeing occurs when the atmosphere is clear and the air is still. Turbulent air produces poor seeing, and fuzzier images.a) the quality of the telescopes optics.b) the transparency of a telescopes lens.c) the sharpness of vision of your eyes.d) the image quality due to air stability.e) the skys clarity & absence of clouds.Point images of a starSmeared overall image of star

37Question 6Adaptive optics refers toa) making telescopes larger or smaller. b) reducing atmospheric blurring using computer control.c) collecting different kinds of light with one type of telescope. d) using multiple linked telescopes.

38Answer: bQuestion 6Adaptive optics refers toa) making telescopes larger or smaller. b) reducing atmospheric blurring using computer control.c) collecting different kinds of light with one type of telescope. d) using multiple linked telescopes.Shaping a mirror in real time can dramatically improve resolution.

Cluster R13639Atmospheric blurring due to air movementsHigh-Resolution Astronomy

Copyright 2010 Pearson Education, Inc.40Solutions: Put telescopes on mountaintops, especially in deserts. Put telescopes in space. Active (adaptive) optics control mirrors based on temperature and orientation.High-Resolution Astronomy

Copyright 2010 Pearson Education, Inc.41Solutions: Without active (adaptive) optics a 1m telescope is limited to about 2With active (adaptive) optics the same 1m telescope could approach 0.1.High-Resolution Astronomy

Copyright 2010 Pearson Education, Inc.42Radio telescopes: Similar to optical reflecting telescopes Prime focus Less sensitive to imperfections (due to longer wavelength); can be made very large Radio Astronomy

105 m Green Bank, WVCopyright 2010 Pearson Education, Inc.43Radio dishes are large becauseQuestion 7radio photons dont carry much energy. they are painted white.c) they are cheap to make.d) they are can operate during the day.

44Answer: aRadio dishes are large in order to Question 7Resolution is worse with long-wave light, so radio telescopes must be large to compensate.radio photons dont carry much energy. they are painted white.c) they are cheap to make.d) they are can operate during the day.

45Largest radio telescope: 300-m dish at AreciboRadio Astronomy

Copyright 2010 Pearson Education, Inc.46Question 8Radio telescopes are useful becausea) observations can be made day & night.b) we can see objects that dont emit visible light.c) radio waves are not blocked by interstellar dust.d) they can be linked to form interferometers.e) All of the above are true.

47Answer: eQuestion 8Radio telescopes are useful becausea) observations can be made day & night.b) we can see objects that dont emit visible light.c) radio waves are not blocked by interstellar dust.d) they can be linked to form interferometers.e) All of the above are true.The Very Large Array links separate radio telescopes to create much better resolution.

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Longer wavelength means poorer angular resolution.Advantages of radio astronomy: Can observe 24 hours a day. Clouds, rain, and snow dont interfere. Observations at an entirely different frequency; get totally different information.Radio AstronomyCentaurus ACopyright 2010 Pearson Education, Inc.49Interferometry: Combines information from several widely spread radio telescopes as if it came from a single dish. Resolution will be that of dish whose diameter = largest separation between dishes.

Radio AstronomyCopyright 2010 Pearson Education, Inc.50Radio Astronomy