Post on 14-Jan-2016
transcript
A105 Stars and Galaxies
News Quiz Today1st NovaSearch homework due Thursday First Exam on Thursday, Sept. 28
Today’s APOD
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
in 6-8 meter telescopes
WIYN TECHNOLOGY
8-10 Meter Telescopes Today• Keck TelescopesGemini North and
South• ESO’s Very Large
Telescope• Subaru• Hobby-Eberly
Telescope and SALT
• MMT Observatory• Magellan• Large Binocular
Telescope
The Twin Keck Telescopeson Mauna Kea
• Two 10-meter telescopes• “segmented” mirrors
– 36 hexagonal segments• Keck I in 1993; Keck II in 1996
ESO’s VLTCerro Paranal, Chile
Four 8.2 meter telescopes– Antu (the Sun)– Kueyen (the Moon)– Melipel (the Southern Cross)– Yepun (Venus - as evening star)
6.5-meter Telescopes
Magellan TelescopesTwin 6.5-m in Chile
Borosilicate honeycomb mirrors
MMT Observatory 6.5-m Telescopealso borosilicate honeycomblocated in southern Arizona
Large Binocular Telescope
Twin 8.4-meter mirrors on a single mount in
southern Arizona
Correcting for Correcting for the Earth’s the Earth’s
AtmosphereAtmosphere
• 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???
UH-88”, Courtesy W.Brandner, 0.65” seeing
4’40”
5”
>220 stars in 5”x5”
Gemini N/Hokupa’a-QUIRC (U of H/NSF)
The Power
ofAdaptive
Optics
• text
The importance of image quality
typical ground-based 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
• 8.4-meters• Triple-fold optical design• 3 billion pixel-camera• 30,000 gigabytes each night
LSSTLarge-apertureSynoptic
SurveyTelescope
Survey the sky each weekReal-time data analysis3 billion sources + transients
Beyond 30-meters
ESO’s Overwhelmingly
Large Telescope
How much do big telescopes cost?
Cost increases rapidly as the
diameter increases
Telescope Cost vs. Aperture0
20
40
60
80
100
120
140
0 5 10 15
Aperture in meters
Co
st (
mil
lio
ns
of
$$)
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