Studying the Universe. Telescopes Telescopes aid astronomers in 2 ways Gather more light than the...
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Transcript of Studying the Universe. Telescopes Telescopes aid astronomers in 2 ways Gather more light than the...
Studying the Universe
Telescopes
Telescopes aid astronomers in 2 ways• Gather more light than the naked eye
• Magnify images
Telescopes Best locations:
• Mountain peaksBecause of thinner air and high elevations
• Desert climatesDry, clear skies
• Remote areasNo city lights
Telescopes
Optical• Use lenses or mirrors to gather and
focus starlight• Kept in domes to protect from the
weather • Light gathering power depends on the
area of the lens or mirror
Refracting Telescope
Two lenses• Objective lens (end away from your eye)
Gathers starlight and bends it to form an image at the other end of the scope
• Eyepiece lens Magnifies the image for your eye
Reflecting Telescopes
One large curved mirror gathers and focuses starlight
The large mirror is the objective Has a secondary mirror to reflect the
image to the observer Also has an eyepiece lens to magnify
the image
Radio Astronomy
The study of radio waves given off by objects in space
Radio waves can pass through clouds of fine dust between stars (light rays can’t)
Can also be used during the day, when the stars can’t be seen
Radio Telescopes Look like satellite
dishes used for TV Made of solid metal
or wire mesh Collects and focuses
radio waves Radio waves have
longer wavelengths, so radio telescopes must be bigger than opticals
MMT
MMT = multiple mirror telescope
Several mirrors take the place of a single large mirror
Less expensive to build than single mirror
Hubble Space Telescope In orbit around Earth to
avoid clouds and be closer to far away objects
Misshapen main mirror and other mechanical difficulties made it less effective
Computers have provided image correction technology so the telescope can be used
Studying Energy
Stars emit light we can see….they also emit energy we cannot see
Electromagnetic energy – includes light, x-rays, radio waves, microwaves
Each type of energy has a different frequency and wavelength
All have the same velocity = 300,000 km per second
Electromagnetic spectrum = the range of wavelengths from radio
waves to gamma rays
Describing Energy Energy travels in waves… Frequency = the number
of waves that pass by a point in one second
Wavelength = distance from peak to peak or trough to trough
Frequency and wavelength are inversely proportional (as one goes up, the other goes down)
Visible Spectrum
Visible spectrum = the range of wavelengths we can see
Each color of the rainbow has a different wavelength and frequency
All of the colors of the rainbow make up “visible” or “white” light
Red has a long wavelength, which means it bends less when passed through a prism
Visible Spectrum
Spectroscope = a prism with a tiny viewing telescope
Separates light into its different colors
Spectrograph = prism with a lens and a camera, which records the spectrum
Visible Spectrum
Seeing the colors of light allow astronomers to determine which chemical elements are present in the star’s outer layers
Spectra also allow astronomers to determine if the star is moving towards us or away from us
Kinds of Visible Spectra
Continuous spectrum – unbroken band of colors, source is sending out all visible wavelengths of light
Can be produced from a glowing solid (light bulb)
Can be produced from a glowing liquid (molten iron)
Can be produced from the hot, compressed gases deep inside a star
Kinds of Visible Spectra
Bright line spectrum – unevenly spaced series of lines of different colors and brightness
Source emits only certain wavelengths of light
aka – emission spectrum Each element (as a gas) has a unique
combination of colors
Kinds of Visible Spectra
Dark line spectrum – continuous spectrum with dark lines where light is absorbed
Dark lines are in the same place as the bright lines
Form when light emitted by a star passes through a cooler gas
Gas absorbs the same wavelengths it would give off if heated
aka – absorption spectrum Used to identify the element
Emission spectra box Tube is filled with a
single element in the gaseous state
Electricity heats up the gas
The gas emits certain wavelengths of light
Combo of colors tells you what element you have