Details Title: ASTRONOMY CHAPTER 6 Description: from book and outline paper Total Flash Cards: 46 Created: 03/05/2009 16:47:30		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Astronomy Flashcards
Cards in this set: Term Define electromagnetic radiation. Definition an electric and magnetic disturbance that transports energy at the speed of light. Term what is light? Definition light is the visible form of electromagnetic radiation Term What does the electromagnetic spectrum include? Definition 1. gamma rays 2. X-Rays 3. Ultraviolet radiation 4. visible light 5. infrared radiation 6. radio waves Term what is a photon? Definition a particle of light Term the amount of energy a photon carries depends on what? Definition it's wavelength Term what is the wavelength of visible light usually measured in? Definition nanometers or angstroms Term what does the wavelength of visible light range betweeN? Definition 400nm to 700nm Term Do radio/infrared radiation have longer or shorter wavelengths? less or more energy? Definition longer wavelengths/less energy Term XRay/gamma ray/ultraviolet radiation have longer or shorter wavelengths? more or less energy? Definition shorter wavelengths/more energy Term what is frequency? Definition the number of waves that pass a point in one second Term what is wavelength related to? Definition frequency Term what two atmospheric windows is Earth's atmosphere transparent in? Definition visible light and radio Term how do telescopes work? Definition telescopes use a primary lens (mirror) or objective lens to gather light and bring it into prime focus where it is magnified by an eyepeice Term how are telescopes limited? Definition short-focal-lengths are more expensive and harder to make Term What does a refracting telescope do? Definition uses a lens to bend the light and focus in on an image. (common with chromatic aberrations--color fringing) Term What do reflecting telescopes do? Definition use a mirror to focus the light. Do not suffer from chromatic aberration (color fringement) Term where does light first come to focus? what do the secondary mirrors do? Definition first comes into focus in PRIME FOCUS. The secondary mirrors DIRECT LIGHT to other focus locations Term what is the difference between resolving power, magnifying power, and light gathering power? Definition resolving power: the ability of a telescope to resolve fine detail magnifying power: ability of a telescope to make an image larger light-gathering power: ability of a telescope to produce bright images Term what does interferometry refer to? Definition to connecting two or more separate telescopes together to act as a single large telescope Term what has replaced photographic plates in most applications? Definition charge-coupled devices (CCD's) Term what does a comparision spectrum allow astronomers to measure? Definition the wave-lengths of spectral lines Term for what three reasons do astronomers use radio telescopes? Definition 1. they can detect cool hydrogen in space 2. they can see through dust clouds that block visible light 3. they can detect certain objects invisible at other wavelengths Term what are cosmic rays? Definition subatomic particles, such as electrons and protons, traveling at nearly half the speed of light Term if you had to choose between a refracter telescope and reflecting telescope, which would you choose and why? Definition a reflecting telescope, because they are less expensive and dont suffer from chromatic aberration Term why do astronomers do their studies outside of the city and on higher surfaces (like mountains)? Definition to avoid light pollution (artifical city lights that dims faint objects). Term what does a spectrograph do? Definition spreads the light out according to wavelength to form a spectrum Term what makes CCD's more useful than photographic plates? Definition CCDs can detect the faintest object and the brightest in a single exposure, more sensitive, and read directly into comp. memory. Term how do astronomers investigate the objects they study? Definition analyze the light and radiation Term Light waves are characterized by what two things? Definition wavelength and frequency (F= speed of light/wavelength) Term what is the speed of light? Definition C=3x10^8m/s Term different colors of light correspond to what two different things? Definition wavelengths and frequencies Term True or False: the energy of a photon depends on the intensity or brightness of light Definition false Term What are the most energetic waves in the electromagnetic spectrum? Definition Gamma Rays Term What do astronomers use telescopes for? Definition to gather more light from astronomical objects (the larger the telescope, the more light it gathers) Term What are the two types of optical telescopes? Definition 1. refracting (uses lens) 2. reflecting (uses mirrors) Term What type are most modern telescopes? Definition reflecting Term What is resolving power? Definition the minimum angle you can use to tell the whats between two objects Term What are the three powers of a telescope? Definition 1. light-gathering power 2. resolving power 3. magnifying power Term What are four types of telescopes? Definition 1. Prime focus 2. Cassegrain Focus 3. Newtonian Focus 4. Coude Focus Term how does adaptive optics use computers to compensate for distortions? Definition by atmospheric turbelance Term What is the proces of combining signals from smaller telescopes to create one larger mirror? Definition interferometry Term What will spectral lines tell us about an object? Definition chemical composition and other properties Term name three factors that radio telescopes allow us to observe. Definition 1. Neutral Hydrogen clouds (contain 90% of all atoms of universe) 2. Molecules 3. regions where visible light is heavily absorbed Term What are the three types of radiation that can only be observed from space? Definition 1. Far-infrared 2. ultraviolet 3. xray radiation (gamma rays) Term if you have a shorter wavelength, do you have a lower or higher frequency? Definition higher Term NOTE: Ultraviolet has shorter wavelengths, infrared has longer wavelengths Definition NOTE: The larger the wavelength, the lower the frequency