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A105
Stars and Galaxies
Today’s APOD
 News Quiz Today
1st NovaSearch homework due Thursday
 First Exam on Thursday, Sept. 28
Announcements…
• Kirkwood Obs. open Weds
night 9:00 – 11:30
• Rooftop Session, Sept. 28,
8:30
Upcoming Events
• Moon Festival at Kirkwood Obs.
–Wednesday, Oct. 4, 8:30-10:30
–sponsored by the Asian Culture
Center
• Transit of Mercury
–Nov. 8, 2:15 PM - Sunset
Space vs.
Ground-Based
Observatories
• 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
Light
Pollution
• artificial
lighting
threatens all
observatories
on the ground
• shield all
outdoor lights
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
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
WIYN image
The Ring Nebula
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?
140
Cost (millions of $$)
Cost increases
rapidly as the
diameter
increases
120
100
80
60
40
20
Telescope Cost vs. Aperture
0
0
5
10
Aperture in meters
15
Homework Review
Homework:
– www.astro.indiana.edu/novasearch
Preparing for the Exam
• Take the 1st two practice tests on Oncourse
• Review Key Terms, Questions for Review,
and “Test Yourself” at the back of each
section we covered
• Sections: 1, 2, 3, (4), 5, 6, 10, 21, 22, 23, 24,
25, 26, 27, 30
• Also review class notes, essential facts,
homeworks
• Test will ask you to APPLY what you
know, not just to repeat back what you
know!
 The Sun! Units 49, 50, 52
 News Quiz on Tuesday
 Homework Due EACH THURS.
EXAM THIS THURSDAY