H205 Cosmic Origins

Telescopes (Ch. 6)Visit Kirkwood ObsTime for Reflection

Hand in EP1

APOD

Beginnings…

This sketch of a telescope was included in a letter

written by Giovanpattista della Porta in August 1609

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 collectsincreases as the area of the primary mirror(the square of the diameter)

Telescopes and

how they work

from lenses…

to mirrors

Kirkwood Observato

ry• 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 Technolog

y• “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

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 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

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

Detecting the Light

• 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)

The Human EyeOnce used with a telescope to record observations or make sketchesNot good at detecting faint light, even with the 10-meter Keck telescopes

•Photographic plates chemically stores data to record fainter light

•Very inefficient: only 4% of the light recorded on film

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 imageThe 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

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 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

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?

•When can I see Hubble?

Where is the Hubble Space Telescope?

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 SpitzerInfrared

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 2Special Lecture:Tuesday, March 24, FA015, 7:30 PMThe Chemical Heritage of Star and Planet Formation

Good for Reflection 1

!!!