Chapter 21, section 1

Tools of Modern Astronomy

By Rusty Sturken

Electromagnetic Spectrum

• Electromagnetic radiation is energy that can travel directly through space in the form of waves

• Electromagnetic spectrum is the range of wavelengths of electromagnetic waves

• Visible light is light that you can see with your eyes

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Electromagnetic Spectrum

Image from http://www.lcse.umn.edu/specs/labs/images/spectrum.gif

Visible Spectrum

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Telescopes• A telescope is a device built to study

distant objects by making them appear closer

• A refracting telescope uses convex lenses to gather a large amount of light onto a small area

• A reflecting telescope uses mirrors to gather a large amount of light onto a small area

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Telescopes• A radio telescope uses curved,

reflecting surfaces to concentrate faint radio waves from outer space onto small antennas

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Refracting telescope

Image on left from http://www.dkimages.com/discover/previews/941/25018530.JPG

Image on right from http://www.adlerplanetarium.org/research/collections/instruments/images/g33_72.jpg

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Reflecting Telescope

Image on left from http://astro-canada.ca/_en/_illustrations/a4304_newton_en_p.jpg

Image on right from http://www.stargazer.htmlplanet.com/telescope.jpg 7

Radio Telescope

Image on left from http://pro.corbis.com/images/RF4411534.jpg?size=572&uid=%7BD0356A80-EEEE-4A3C-ACBA-86BB2F75551D%7D

Very Large Array Telescope

Image on right from http://www.aoc.nrao.edu/~emomjian/ao002.jpg

Arecibo Radio Telescope

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Hubble Space Telescope

Image from http://www.sc.gov/NR/rdonlyres/93C9CEAE-361E-4F3B-B4C4-CEDD151A6321/2769/FloatingHubble.jpg 9

Spectrographs• A spectrograph breaks light from an

object into colors and photographs the resulting spectrum. It can tell:– Chemical composition of a star– Temperature of a star

Image from http://www.astrosurf.com/aras/dearden/Telescope&Spectrograph2.jpg

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Spectrographs

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Spectrographs

Image from http://www.scienceinschool.org/repository/images/issue4spectrometer11_large.jpg12