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 WAVELENGTHblue shift
• Star Approaching
•Star Receding
RED-SHIFTING STAR (Moving
Away From Us)
BLUE-SHIFTING STAR
(Moving Towards Us)
Red or blue shift?
sun
Star MOVING AWAY from us.
(RED-SHIFTING)
REFERENCE SPECTRUM
Mauna Kea Observatory
Mauna Kea
Aug. 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 AZ
discovered 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 Observatory
10 m reflector
largest in world
LBT
Large Binocular Telescope
• Two 8.4 m mirrors
CATADIOPTRIC TELESCOPES
combines 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 Array
Socorro, NM
• Arrays use many telescopes that act as one
telescope
Very Large Baseline Array Sites
Hawaii California
New Hampshire
Kitt Peak,
Washington
New Mex. Texas
Iowa
New Mex.
40 meter radio telescope
Green Bank, WV
305 meter
Arecibo Radio Telescope
Signal is received
by telescope
Signal is amplified
Janskies
Signal is converted to false colors
Minutes
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 telescope
launched 2003
GLAST- gamma ray telescope
Chandra X-ray telescope
launched 1999
HUT (HOPKINS UV
TELESCOPE)
Clumpy universe
GALEX UV
COBE
microwave