A105 Stars and Galaxies  News Quiz Today  1 st NovaSearch homework due Thursday  First Exam on Thursday, Sept. 28 Today’s APODAPOD

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 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)

6.5-meter Telescopes Magellan Telescopes Twin 6.5-m in Chile Borosilicate honeycomb mirrors 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???

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 of Adaptive 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 Bigger than a football field! 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 LSST Large-aperture Synoptic Survey Telescope  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

Homework Review Homework: –

Preparing for the Exam Take the 1 st 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