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How do we study the Universe?
SPECTROSCOPY
• Uses visible wavelength split into colors
Doppler shift
• Wavelengths change when object is moving
Red/ Blue Shift
• RECEDING (moving away) objects show a INCREASE in WAVELENGTH- red shift
• APPROACHING objects show a DECREASE in WAVELENGTH- blue shift
• Star Approaching
• Star Receding
RED-SHIFTING STAR (Moving Away From Us)
BLUE-SHIFTING STAR (Moving Towards Us)
sun
Red or blue shift?
Star MOVING AWAY from us.(RED-SHIFTING)
REFERENCE SPECTRUM
Mauna Kea Observatory
Mauna KeaAug. 2011
Optical telescopes
• Need clear weather• Away from city lights (light pollution)• Above clouds (mountain tops)
– Less distortion
• Many in AZ and HI
Kitt Peak, Arizona
REFRACTING TELESCOPES
Use multiple lenses to focus light and magnify images.
The USNO 26-inch Refracting Telescope
REFRACTORS• Lenses are expensive• Chromatic aberration (halo affect;bad)• good for observing solar system objects
• See details (good contrast)
Lowell Observatory, Flagstaff AZdiscovered Pluto
24” refractor
REFLECTING TELESCOPES
Uses a series of mirrors to gather and focus light.
Reflectors
• Mirrors are cheaper • See farther than refractors
– Lose detail
• Can build larger (10 meters vs. 1 meter)• “Coma” problem
“coma problem
• Stars need edge of field have “tails”
8” REFLECTOR
Keck Observatory10 m reflector
largest in world
LBTLarge Binocular Telescope
• Two 8.4 m mirrors
CATADIOPTRIC TELESCOPEScombines the best features of refractors and reflectors
Dobsonian telescope
• Cheap • Reflector• need dark skies• Only azimuth mount• Good beginner telescope
Radio telescopes
• Gather incoming radio waves• Convert waves to colors• Produce false color images
Radio telescopes
• Best for out of solar system objects– Galaxies– Supernovas– quasars
Very Large ArraySocorro, NM
• Arrays use many telescopes that act as one telescope
Very Large Baseline Array Sites
Kitt Peak, AZ
New Mex. Texas New Mex. Virgin Islands
Hawaii California Washington Iowa New Hampshire
40 meter radio telescope
Green Bank, WV
305 meterArecibo Radio Telescope
Signal is received by telescope
Signal is amplified
Jan
skie
s
Minutes
Signal is converted to false colors
SUPERNOVA REMNANT
All declinations combined make a picture
THE MOON
A GALAXY
Jupiter
Planet forming
Advantages of Radio Telescopes
• Use anytime (day, clouds, etc)• No dome needed• Detect object much further away
Infrared
Advantages of Space Telescopes
• No atm. Interference– See clearer
• NOT CLOSER• Can detect wavelength
that atm. blocks
Hubble
• reflector• Last service mission (2010) will keep
operating to at least 2014
• In 2018 Hubble will be replaced by James Webb telescope (IR)
James Webb telescope
• Mission length: 5 years • Remain stationary above Earth
Hubble vs. Webb
Other space telescopes
Spitzer infrared telescopelaunched 2003
GLAST- gamma ray telescope
Chandra X-ray telescopelaunched 1999
HUT (HOPKINS UV TELESCOPE)
Clumpy universe
COBEmicrowave