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H205
Cosmic Origins
APOD
Telescopes (Ch. 6)
Visit Kirkwood Obs
Time for Reflection
Hand in EP1
This sketch of a telescope
was included in a letter
written by Giovanpattista
della Porta in August 1609
Beginnings…
Thomas Harriet’s
Drawings of the Moon
and Sun
Technology moves
forward… Telescopes
get BIGGER
Think about a square telescope…
Round ones work the same way
The amount of light a
telescope collects
increases as the area
of the primary mirror
(the square of the
diameter)
Telescopes
and
how they work
to
mirrors
from
lenses…
Kirkwood
Observatory
• 12” refracting
telescope (uses lenses
to form an image)
• Built in 1901
• Used for public
outreach and teaching
The 3.5-meter WIYN telescope
Kitt Peak, Arizona
The WIYN
Telescope
• Mirror: 3.5
meter diameter
• Located at Kitt
Peak, Arizona
• Built in 1995
• IU has a share
New
Telescope
Technology
•
• “Fast” mirror
• Lightweight mirror
Mirror shape controlled
• Mechanically simpler
mount
• Temperature control
Casting the
WIYN Mirror
Polishing the
WIYN Mirror
The WIYN New Technology “Dome”
•
•
•
•
Compact telescope chamber
Open for ventilation
Insulated to keep cool
Heated spaces kept separate
WIYN TECHNOLOGY
in 6-8 meter telescopes
8-10 Meter
Telescopes Today
• Keck Telescopes
 Gemini North and South
• ESO’s Very Large
Telescope
• Subaru
• Hobby-Eberly Telescope
and SALT
• MMT Observatory
• Magellan
• Large Binocular
Telescope
The Twin Keck
Telescopes
on Mauna Kea
• Two 10-meter telescopes
• “segmented” mirrors
– 36 hexagonal segments
• Keck I in 1993; Keck II in
1996
ESO’s VLT
Cerro Paranal, Chile
Four 8.2 meter telescopes
–
–
–
–
Antu (the Sun)
Kueyen (the Moon)
Melipel (the Southern Cross)
Yepun (Venus - as evening star)
Magellan Telescopes
Twin 6.5-m in Chile
Borosilicate
honeycomb
mirrors
6.5-meter
Telescopes
MMT Observatory 6.5-m Telescope
also borosilicate honeycomb
located in southern Arizona
Large Binocular
Telescope
Twin 8.4-meter mirrors
on a single mount in
southern Arizona
Going Observing
• To observe at a major observatory, an
astronomer must:
– Submit a proposal
– Plan ahead
– Work day and night
• Astronomers may also “observe” via the
Internet
– Space observatories
– Data archives
– Remote observing – We will do this!
Computers
• Operating a computer and being able to
program are as important as knowing how to
use a telescope
• Computers accomplish several tasks:
– Solve equations
– Move telescopes and feed information to
detectors
– Convert data into useful form
– Communicate and distribute data
The Human Eye
Once used with a telescope to record
observations or make sketches
Not good at detecting faint light, even
with the 10-meter Keck telescopes
Detecting
the Light
•Photographic plates chemically
stores data to record fainter light
•Very inefficient: only 4% of the
light recorded on film
• Electronic Detectors
– Incoming light strikes an
array of semiconductor
pixels that are coupled to a
computer
– Efficiencies of 95% are
possible
– CCD (Charged-coupled
Device)
Correcting for
the Earth’s
Atmosphere
• Even at wavelengths where the atmosphere is
transparent, the atmosphere “blurrs” light
– Why to stars “twinkle” (scintillation)?
– The condition of the sky for viewing is referred to
as seeing
– Distorted seeing can be improved by adaptive optics
Adaptive Optics –
Correcting distortions caused
by the Earth’s Atmosphere
How does it work???
The
Power
of
Adaptive
Optics
40”
4’
5”
>220 stars in 5”x5”
UH-88”, Courtesy W.Brandner, 0.65” seeing
Gemini N/Hokupa’a-QUIRC (U of H/NSF)
The importance of
image quality
• text
typical groundbased image
Hubble image
The Ring Nebula
WIYN image
New Telescopes to Answer
New Questions
•
•
•
•
20 and 30-meter telescopes
8-meter survey telescope
James Webb Space Telescope
Virtual Observatory
Adaptive Optics
will be a key
component of 20
and 30 meter
telescopes
Lasers will produce
artificial stars in the
sky to help focus
starlight
Large-aperture
Synoptic
Survey
Telescope
•
•
•
•
8.4-meters
Triple-fold optical design
3 billion pixel-camera
30,000 gigabytes each night
LSST
Survey the sky each week
Real-time data analysis
3 billion sources + transients
Beyond 30-meters
ESO’s
Overwhelmingly
Large Telescope
How much do big telescopes cost?
Cost
increases
rapidly as the
diameter
increases
Light
Pollution
• artificial
lighting
threatens all
observatories
on the ground
• shield all
outdoor lights
Electromagnetic Spectrum
Is the Atmosphere Transparent or Opaque?
Applets\light_absorption.swf
Observing at Nonvisible
Wavelengths
• Astronomical objects radiate in wavelengths
other than visible (thermal radiators)
– Cold gas clouds
– Dust clouds
– Hot gases around black holes
• Telescopes for each wavelength region
–
–
–
–
Require their own unique design
All collect and focus radiation and resolve details
False-color pictures to show images
Some wavelengths must be observed from space
Radio Telescopes
• Radio telescopes work
the same way as optical
telescopes
• Large metal “mirror”
reflects radio waves
• Space-Based Advantages
– Freedom from atmospheric blurring
– Observe at wavelengths not transmitted by air
• Ground-Based Advantages
– Larger collecting power
– Equipment easily fixed
• Ground-Based Problems
– Weather, humidity, and haze
– Light pollution
Space vs. GroundBased
Observatories
Exploring New
Wavelengths:
Gamma Rays
• 1967 gamma-ray bursts from space discovered by
military satellites watching for Soviet nuclear bomb
explosions
• Source of gamma-ray bursts is now (almost)
understood
• Gamma rays from Milky Way center and remnants of
exploded stars
Space Telescopes
• NASA’s four Great Observatories
–
–
–
–
Visible – Hubble Space Telescope
Gamma rays - Compton Gamma Ray Obs.
X-rays - Chandra X-ray Observatory
Infrared - Spitzer Space Telescope
The Hubble Space Telescope
Hubble
Trivia
• Launched April 24, 1990, by
Space Shuttle Discovery
• Visible light, ultraviolet, and
near-infrared
• Orbits about 380 miles (611
km) above Earth
• About the size of a bus
• Primary mirror ~ 2 meters
• Named after astronomer
Edwin Hubble
– discovered galaxies beyond our
Milky Way
– determined that space is
expanding
Keeping track of
Hubble
• Where is Hubble now?
Where is the Hubble Space Telescope?
• When can I see Hubble?
www.heavens-above.com
Space and
Ground in
Partnership
• Supernova brightness
measured with Hubble
• Distances measured
from the ground
The
Chandra X-Ray
Telescope
How Do X-Ray Telescopes Work?
•
•
•
•
X-rays do not reflect off mirrors the same way that visible
light does
X-ray photons penetrate into the mirror in much the same way
that bullets slam into a wall
X-rays ricochet off mirrors like bullets off a wall
X-ray telescopes are very different from optical telescopes.
X-ray mirrors are
precisely shaped
and aligned to
incoming x-rays.
They look more
like barrels than
the familiar dish
mirrors of optical
telescopes.
The Spitzer
Infrared
Space
Telescope
Spitzer
Trivia
•
•
•
•
Launched 25 August 2003
Estimated Lifetime:2.5 – 5 years
Orbits the Sun, Earth-trailing, heliocentric
Telescope – only 85 cm diameter (33.5”)
www.spitzer.caltech.edu/about/now.shtml
Compton Gamma Ray
Observatory
• 1991 – 2000
• solar flares
• gamma-ray bursts
• pulsars
• nova
• supernova explosions
• black holes
• quasar emission
What does it cost?????
• Proposed NASA budget for 2009:
~$18 B
– Science
–
–
–
–
~$5.3 billion
*
Exploration
~$5.0 billion
Aeronautics
~$0.7 billion
Space Ops
~$7 billion
Education
~$0.15 billion
*All astronomy research and space
telescopes are in this part.
Comparable Spending
•
•
•
•
•
•
•
•
$20 billion at jewelry stores (US)
$24 billion at liquor stores (US)
$40 billion on weight loss (US)
$23.5 billion on candy and gum (US)
$31 billion on pet toys and supplies (US)
$7 billion on video rentals (US)
$18 billion on makeup (worldwide)
$35 billion on bottled water (worldwide)
Great Observatories’ Costs
•
•
•
•
Hubble Space Telescope: $6 billion
Chandra X-ray Telescope: $2.5 billion
Spitzer IR Telescope: $1.2 billion
Compton Gamma Ray Tel: $0.56 billion
Question: Why does society chose to
support science research at this cost?
For Week 2:
Chapter 23 (Origin of Universe)
Chapter 4 (Gravity)
EP 2
Special Lecture:
Tuesday, March 24, FA015, 7:30 PM
The Chemical Heritage of Star and
Planet Formation
Good for
Reflection 1
!!!