Tools of Astronomy

Study of Light

• Newton (1666): studied light traveling through a prism & saw a spectrum of colors: ROYGBIV

• Huygens (1670s): determined light travels in waves; shorter wavelengths are refracted (bent) more than longer wavelengths– Led to the creation of spectroscopy—the science

of the properties of light

Sun’s Light

• Spectroscopesbreak Sun’s light into the various colors, each with its own wavelength

• ROYGBIV=visible spectrum• Visible spectrum is only a small part of

the entire spectrum of electromagnetic radiation given off by stars/galaxies

EM radiation

• Electromagnetic waves --> range of electric and magnetic waves that travel through space– transfer energy– travel through space– travel at the speed of light—300,000 km/s

• Include:– UV light=sunburns– Infrared=heat– X-rays, microwaves, gamma rays (CT scans)

Electromagnetic Spectrum: the continuum of radiation released by star--classified by wavelength (red longer, blue shorter)

--wavelength=distance between the peaks on a wave--frequency=the # of waves that pass a point per second

As wavelength decreases, freq. increases they are inversely proportional

How is this info. used by astronomers?

• Visible light= temp of stars• spectrums of common elements in stars• Radio telescopes=pick up radio emissions to create images of the

object• Refracting tele: lenses bring light into focus• Reflecting tele: mirrors bring light into focus• Interferometry: combines several telescope images to make a very

detailed image• X-ray telescopes=picks up energy (radiation) from supernova

explosions, galaxies & black holes• Hubble telescope=infrared instruments pick up nebulas & cool stars

• Gamma rays viewed when observing the moon

• X rays shot at a heavy metal (beneath the hand) that can be processed to show density

• Hubble-low Earth orbit; 1990 (in)-2013/2021(out); 347 mi above Earth (reflecting telescope)– Why send a telescope into outerspace? 1) The earth's atmosphere distorts and

blurs images, so the Hubble produces images much clearer than those that can be produced on earth (although there have also been improvements in technology for earth-based telescopes).

2) Some frequencies are absorbed by the atmosphere, and can only be observed from space. This is why we have launched telescopes to view the universe in a variety of frequencies (gamma ray, X-ray, infrared, etc.)

Sun (l) and Galaxy collisions (r)X-ray telescope images