ASTR 151 1st Edition Lecture 6 Outline of Last Lecture I. 1.4 Earth`s Orbital MotionII. 1.5 Motion of the MoonIII. 1.6 Measurement of DistanceOutline of Current LectureI. 5.1 Optical TelescopeII. 5.2 Telescope SizesIII. 5.3 Images and DetectorsIV. 5.4 Atmospheric blurringCurrent LectureI. 5.1 Optical telescopea. Optical Telescopes collects visible light and focuses it at one pointi. Visible light – small part if the electromagnetic spectrum energy carried by waves is proportional to waves is proportional to wave frequency /inversely proportional to wavelengthb. Galileo`s first telescope was a refracting telescopei. He discovered Europa, one of Jupiter`s moons; not Neptuneii. His telescope only magnified 3 times c. Refracting Telescopesi. Refraction – change in the direction of a wave association with change of transmission mediumii. Refraction – lens – depends on energy/ frequency/ wave lengths of lightiii. Lenses onlyiv. Long skinny tubev. (M) = (F^o) focal length of optical tube/ (F^e) local length of eye piecevi. Chromatic aberrationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.d. Reflecting Telescopesi. Reflecting mirror depends on the size of the lensii. Most modern telescopes are reflectors1. Some light is refracted while others are absorbed2. It depends on the wavelengthiii. Large lenses work best but they are also heavy and hard to support1. Needs a smaller lens to usee. Types of Reflecting Telescopesi. Four types;1. Prime2. Neurtonian3. Cassegrain4. Nasmyth/ coud`e focusII. 5.2 Telescope Sizesa. Larger Mirror = larger amounts of information that can be gatheredi. Resolving power - can distinguish objects when by their sides if telescope is goodb. Angular Resolution – smallest distance between two resolvable objectsi. Measured in arc seconds arcsec = 0.25(wavelength /diameter)III. 5.3 Images and Detectorsa. Image Acquisitioni. Subdivided by 2demisional array of pixels (picture-elements)1. Was used because 1 photon = 1 quantum of energy2. Easy to shareii. Computers process and “analyze” imagesb. Observatoriesi. Usually found in highest elevations and in deserts to avoid atmospheric “noise” and airIV. 5.4 Atmospheric blurringa. Atmospheric Blurringi. Called “seeing”; point sources out as speckle plattersii. Long exposure imagesb. Earth base Telescopesi. High altitudesii. Harder to breathe due to less air and water
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