chapter 24 sec. 1 light sec. 2: tools of astronomy
DESCRIPTION
24.1 Electromagnetic Radiation Electromagnetic waves --> Range of electric and magnetic waves that travel through space transfer energy Classified based on wavelength travel through space travel at the speed of light—~300,000,000 m/s Include: Ultraviolet (UV) light=sunburns Infrared radiation=heat Visible light X-rays Microwaves Radio waves Gamma rays (CT scans)TRANSCRIPT
Chapter 24 Sec. 1 Light Sec. 2: Tools of Astronomy 24.1
Electromagnetic Radiation
Electromagnetic waves --> Range of electric and magnetic waves
that travel through space transfer energy Classified based on
wavelength travel through space travel at the speed of
light~300,000,000 m/s Include: Ultraviolet (UV) light=sunburns
Infrared radiation=heat Visible light X-rays Microwaves Radio waves
Gamma rays (CT scans) Light is ... Nature of Light Behaves like a
wave
Similar to swells in the ocean Wavelength Distance from crest to
crest Behaves like a particle Photon Small packet of light energy
Spectroscopy Spectroscopy
Study of the properties of light that depend on wavelength Break
light into the various colors, each with its own wavelength Three
types of Spectra Continuous Absorption Emission Spectroscopy:
Continuous
Uninterrupted band of light Emitted by an incandescent solid,
liquid, or gas under pressure. Spectroscopy: Absorption
Continuous spectrum produced when white light passes through cool
gas under low pressure. Spectroscopy: Emission
Series of bright lines of particular wavelengths produced by a hot
gas under low pressure. Used to study the spectrum of a star:
Spectral lines act as fingerprints Lines identify elements present
stars chemical composition 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 Doppler Effect The Doppler Effect: Sound Waves
Electromagnetic Waves Apparent change in frequency of
electromagnetic or sound waves caused by the relative motions of
the source of the observer. Used to determine whether a star or
other body in space is moving away from or toward Earth. The Best
Halloween Costume Ever 24.2 How Is This Used By Astronomers?
Telescopes: Refracting telescope Reflecting telescope Both types
have 3 properties that aid astronomers: Light-gathering power
Resolving power Magnifying power Interferometry: combines several
telescope images to make a very detailed image VLT (Very Large
Telescope @ European Southern Observatory (reflecting) Refracting
Telescope Lenses bring light into focus
Bends (refracts) light Objective lens produces image by bending
light from distant object light area called focus (central point)
Refracting Telescope Yerkes Observatory Wisconsin 40 diameter
lens
63 long tube Reflecting Telescope Reflects light off a concave
mirror
Focuses image in front of the mirror Advantages: Most large optical
telescopes are reflectors Light does not pass through a mirror
glass for a reflecting telescope doesnt have to be of optical
quality Reflecting Telescope Keck Telescopes Hawaii Detecting
Invisible Radiation
Radio Telescopes Observations using radio wavelengths Focuses
incoming radio waves on antenna Absorbs and transmits waves to
amplifier Radio Telescopes Advantages:
Less affected by turbulence in the atmosphere, clouds and the
weather No protective dome is required reduces cost of construction
Can see through interstellar dust clouds that obscure visible
wavelengths Space Telescopes Orbit above Earths atmosphere and thus
produce clearer images then Earth-based telescopes Hubble Space
Telescope 1st space telescope built by NASA Put into orbit around
Earth April 1990 Other Space Telescopes Study X-Rays: NASA uses
Chandra X-Ray Observatory (launched in 1999) Study Visible and
Gamma Rays: Compton Gamma-Ray Observatory Infrared: James Webb
Space Telescope James Webb Space Telescope
Infrared vision that will peer back over 13.5 billion years to see
the first stars and galaxies forming out of the darkness of the
early universe. Will launch in 2018 from European Spaceport located
near Kourou, French Guiana on a rocket. (The mission lifetime is
years.)