Reflective Refractive Spectro scopy Space Large telescopes How Optical works $200 $200 $200 $200 $200 $200 $400 $400 $400 $400 $400 $400 $600 $600 $600 $600 $600 $600 $800 $800 $800 $800 $800 $800 $1000 $1000 $1000 $1000 $1000 $1000 $200 Draw a convex lens $400 The lens are made of glass and the larger they are , the more heavy and more flawed they can be. Why are refractive telescopes usually smaller than reflective? $600 Reflective A telescope with a convex mirror and an eyepiece on the side is a $800 They gather more light and have better resolution Why might you want a larger scope than a smaller one? $1000 The Cassegrain needs a hole drilled in the middle of the primary mirror for the eyepiece and its secondary mirror in convex rather than flat. Why is a Newtonian reflector easier to build than a Cassegrain? $200 Reflection The process when Photons bounce off a polished surface $400 Refraction The tendency of a wave to bend as it passes from one transparent medium to another is $600 Chromatic aberration Fuzziness in your lens is caused by $800 CCD’s are faster at capturing light so shorter exposure time. The image is digital, no wait time to be developed. The image is stored on computers, so can be transmitted via the Internet Why is a CCD better than photography for telescopes? $1000 Reflectors use a concave mirror to reflect light back to a focus, refractors use a convex lens to bend light to a focus. Compare how a reflector makes an image versus a refractor $200 radio The lowest energy EM radiation is $400 Most information we receive about the Universe comes in EM waves, especially light. We can get temperature, compostion and motion from a spectrum Why do astronomers relie on spectroscopy? $600 An emission spectrum of bright lines (Kirchoff’s 2nd law) A nebula is a low density cloud of hot gas, what is its spectrum? $800 Using a prism or diffraction gratings where thin slits diffract light. Describe two ways that light is separated out into its component colors for spectroscopy $1000 1st Law: dense hot objects create a continuous spectrum 2nd law: low density gas gives off bright emission lines 3rd law: cool thin gas creates dark lines in the spectrum Describe Kirchoff’s three laws $200 Turbulence or star twinkling Adaptive optics help correct $400 NO. Is it true that the HST is the Largest telescope ever built? $600 Infrared and Ultraviolet Besides visible light, Hubble does work in what two other wavelengths? $800 X-rays The Chandra uses which kind wavelength to form images? $1000 Adaptive optics are for poor visibility due to atmospheric blurring, Hubble is in space! Why doesn’t the Hubble Telescope need adaptive optics? $200 To collect light and bring it to focus The primary purpose of telescopes is to $400 Poor resolution due to the large wavelength What is the downside of radio telescopes? $600 Interferometry Using multiple telescopes to enhance resolution via computers is called $800 The atmosphere blocks most UV radiation Why is UV astronomy hard to do from the ground? $1000 Can be used in daytime and night. Less effected by weather/ Allow us to see objects at different wavelength than visible light. Name three ways that radio telescopes have an advantage over optical telescopes. $200 To get above the influences of our atmosphere Why do we put telescopes in space? $400 resolution The ability to distinguish between two adjacent objects is $600 The resolution is 2x’s as sharp and can now detect 4x’s as dim of objects. How does doubling the diameter effect resolution and light? $800 Stars do not twinkle in space but as they pass through our atmosphere the light is shifted by turbulence. Why do stars appear to twinkle? $1000 The object has already flipped over since the eyepiece lies behind the focal point. Why is the image in a telescope eyepiece inverted?