How do we study the Universe?

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

GALEX UV

COBEmicrowave