Chapter 24 Studying the Sun

StudyBlue printing of Chapter 24 Studying the Sun html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, font, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td { margin: 0; padding: 0; border: 0; outline: 0; font-size: 100%; background: transparent; } body { line-height: 1; } blockquote, q { quotes: none; } blockquote:before, blockquote:after, q:before, q:after { content: ''; content: none; } /* remember to define focus styles! */ :focus { outline: 0; } /* remember to highlight inserts somehow! */ ins { text-decoration: none; } del { text-decoration: line-through; } /* tables still need 'cellspacing="0"' in the markup */ table { border-collapse: collapse; border-spacing: 0; } /* end RESET */ .header { min-width:800px; } .logo { padding:6px 20px 2px 20px; margin:0; font-size:25px; 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microwaves, and radio waves -electromagnetic spectrum -the arrangement of waves according to wavelengths and frequencies -all energy regardless of wavelength travels through the vacuum of space at the speed of light -300,000 km per second -in a 24 hour day it would total 26 billion km -light can be described in two ways -waves -particles -wavelengths vary from several km for radio waves to less than a billionth of a centimeter for gamma rays -most are either too long or too short for us to see -visible light -band of electromagnetic radiation we can see -photons -unexplained -they can push on matter -particles -each has a specific amount of energy -related to wavelength -shorter have more energy -longer have less energy -spectroscopy -introduced by Isaac Newton -3 kinds of spectra exist -study of the properties of light that depend on wavelength -continuous spectrum -produced by an incandescent solid, liquid, or gas under high pressure -incandescent means to emit light when hot -an uninterrupted band of color -absorption spectrum -produced when visible light is pass through a relatively cool gas under low pressure -the gas absorbs selected wavelengths of light emission spectrum -produced by hot gas under low pressure -series of bright lines of particular wavelengths depending on the gas that produces them -most stars are absorption spectrum -when the spectrum of a star is studied the spectral lines act as finger prints -used to identify the elements present and thus the star's chemical composition -Doppler effect -perceived change in wavelength of a wave that is emitted from a source that is moving away or toward an object -the light from a source that is moving away from an observer appears redder because the waves are lengthened -used to determine whether a star or other body in space is moving away from or toward Earth 24.2 Tools for Studying Space -Keck Telescope -located on Mauna Kea in Hawaii -uses mosaic of 36 6-sided, 1.8 meter mirrors -type of optical telescope -Galileo is considered to be the first person to have used telescopes for astronomical observations -built one of his own -refracting telescope -uses a lens to bend or refract light -objective lens -most important lens in a refracting telescope -produces an image by bending light from a distant object so that the light converges at an area called the focus -for an object such as a star the image appears as a point of light -for nearby objects it appears as an inverted replica of the original -if an object is viewed directly a second lens, the eyepiece is required -magnifies the image produced by the objective lense -suffer a major optical defect -light passes through a lens the shorter wavelengths of light are bent more than the longer wavelengths -red, blue, and violet light are out of focus -known as the chromatic aberration -Reflecting telescopes -use a concave mirror that focuses the light in front of a mirror rather than behind it, like a lens -mirror is generally made of glass -able to view the image without blocking too much incoming light -difficult to produce a large piece of high quality, bubble-free glass for refracting telescopes -most large optical telescopes are reflectors light does not pass through a mirror so the glass for a reflecting telescope does not have to be of optical quality -both refracting and reflecting telescopes have three properties that aid astronomers in their work 1) light-gathering power 2) resolving power 3)magnifying power -telescopes with large objectives have a greater resolving power -allows for sharper images and finer detail -gamma rays, x-rays, ultraviolet radiation, infrared radiation, and radio waves are also produced by stars -a narrow band of radio waves is able to penetrate the atmosphere -detection is accomplished by big dishes called radio telescopes -focuses the incoming radio waves on an antenna which absorbs and transmits these waves to an amplifier just like a radio antenna -radio waves are about 100,000 times longer than visible radiation -radio telescopes have poor resolution -radio interferometer -network of radio telescopes wired together -produces a clear image -radio telescopes are less affected by turbulence in the atmosphere, clouds, and the weather -they can also see through interstellar dust clouds that obscure visible wavelengths -they can detect clouds of gases too cool to emit visible light -these are the sites of star formation -optical telescopes are affected by the atmosphere -space telescope -orbit above Earth's atmosphere and thus produce clearer images than Earth-based telescopes -Hubble Space Telescope -first space telescope -built by NASA 24.3 The Sun -no sharp boundaries exist between its various layers -its made of gas -the sun can be divided into 4 parts -solar interior -visible surface (photosphere) -chromosphere -corona -photosphere -radiates most of the sunlight we see -layer of gas less that 500 km thick -neither smooth nor uniformly bright -grainy texture -made of granules -small relatively bright markings -due to rising gases below -gas spreads, cools, and falls back into interior -convection -responsible for the transfer of energy in the uppermost part of the sun's interior -chromosphere -layer of hot gases a few thousand km thick -observable only during a total solar eclipse -consists of hot, incandescent gases under low pressure -produces an emission spectrum -reverse of the absorption spectrum of the photosphere -corona -outermost portion of the solar atmosphere -means crown -visible only when photosphere is covered -envelope of ionized gases -extends a million km -ionized gases have speeds great enough to escape gravitational pull -makes solar wind -travels through solar system -atmosphere protects us -sunspots -Galileo concluded that these were part of sun's surface -used them to find out that sun's equator rotates once in 25 days -location 70 degrees from solar equator requires 33 days -appear dark because of their temperature -used to be believed that they were Vulcan, a planet inside the orbit of Mercury -Prominences -huge cloudlike structures consisting of chromospheric gases -appear as great arches that extend well into the corona -ionized gases trapped by magnetic fields that extend from regions of intense solar activity -Solar flares -brief outbursts that normally last about an hour -appear as a sudden brightening of the region above a sunspot cluster -release enormous amounts of energy -in the form of ultraviolet, radio, and X-ray radiation -cause solar wind -causes auroras -near magnetic pole -nuclear fusion -converts for hydrogen nuclei into the nucleus of a helium atom -tremendous energy is released -some matter is actually converted to energy -E = mc 2 - -E equals energy -m equals mass -c equals the speed of light