Exploring the Universe with Telescopes and Light

Dr. Frank Summers

Space Telescope Science Institute

December 5, 2008

How Telescopes Changed Astronomy

Tycho Brahe

1546-1601

Galileo

1609 – First use of telescope for astronomy

Refracting Telescope

• Two glass lenses

• Long tube

• Refract – light bends

Yerkes 40 inch

1895

60 feet long

Telescope Qualities

• Resolution– See small things– Refractor - long tube

• Light Gathering– See faint things– Refractor - large lens

Isaac Newton 1668 reflecting telescope

Reflecting Telescope

• Mirrors to collect and focus light

• Lens as eyepiece

• Reflect– light bounces

• Shorter tube

• Larger mirrors

Herschel 7 foot

1780s

6.2 inch mirror

Leviathan 1845 72 inch mirror 54 feet long

Mount Palomar 1948 200 inch mirror

http://amazing-space.stsci.edu/resources/explorations/groundup/

http://amazing-space.stsci.edu

From Astrometry to Astronomy

Galileo

1610 Siderius Nuncius

Riccioli

1651

Galileo

1610

Messier

1774

Messier

1774

Draper

1882

Hubble

2006

Build a Refracting Telescope

Hands-On Optics

• Inquiry-based activities• Collaboration

– International Society for Optical Engineering– Optical Society of America– National Optical Astronomy Observatory– National Science Foundation

• http://www.hands-on-optics.org

Hands-On Optics

• Terrific Telescopes– Selected three activities– Significantly abbreviated

• Module 3: Magnificent Magnifications– sciencefirst.com $475 classroom kit

Simple Magnifiers

• Materials– Thinner lens– Thicker lens– Astronomy picture

• Always handle lenses by edges

• Handout for reference

Simple Magnifiers

1. Hold a lens about an inch away from picture.

2. Move lens toward and away from picture.

3. Try it with the other type of lens.

Simple Magnifiers

• Which lens magnifies more?

• At what distance does magnification cease?

Simple Magnifiers

• Which lens magnifies more?

• At what distance does magnification cease?

• Thinner lens – 20 cm focal length

• Thicker lens – 7.5 cm focal length

Build a Refracting Telescope I

• Materials– Thinner lens (20 cm focal length)– Thicker lens (7.5 cm focal length)

• Always handle lenses by edges

• Handout for reference

Build a Refracting Telescope I

1. Hold the thinner lens in front of the thicker lens and examine a distant object.

2. Now try the thicker lens in front of the thinner lens. (This can be difficult.)

Build a Refracting Telescope III

• Materials– Cardboard tubes (inner and outer)– Plastic bag of optics

• Large lens• Cardboard washer• Cap• Small lens• Foam eyepiece holder• Cardboard spacer

• Always handle lenses by edges• Handout for reference

Build a Refracting Telescope III

1. Put curved side of large lens against end of outer tube. Add washer and cap.

2. Push small lens into foam eyepiece holder.

3. Slide cardboard spacer into foam eyepiece holder against the flat side of small lens.

4. Slide foam eyepiece holder into inner tube with cardboard spacer toward end.

Build a Refracting Telescope

• How does a plano-convex lens differ from a double convex lens?

• What knowledge or skills would be important in making telescopes?

• How might professional telescopes differ from these simple models?

Exploring with Light and Color

Exploring Visible Light

Exploring Visible Light

• Where do the colors come from?

• What is the difference between light of different colors?

Exploring Visible Light

Exploring Emission Spectra

• Materials– Discharge tubes– Power supplies– Diffraction grating glasses

• Do not touch tubes or power supply– HIGH VOLTAGE

• Teacher Handout• Student Handout

Exploring Emission Spectra

1. Observe the gas tube with your eyes.

2. Observe the gas tube through the diffraction glasses.

3. Repeat for other gas tubes.

Exploring Emission Spectra

• Where might astronomers see emission spectra?

• What information would an emission spectra provide?

Spectrum of the Sun – Type G2 Star

Spectrum of Arcturus – Type K1 Star

Spectrum of Procyon – Type F5 Star

The Universe Beyond Your Eyes

Hubble Space Telescope

Spitzer Space Telescope

Chandra X-ray Observatory

Chandra

Hubble

Spitzer

Compton

How Light is Used as a Tool

• Materials– Electromagnetic spectrum poster

• Teacher Handout

• Student Handout

How Light is Used as a Tool

1. Identify a feature that is visible in several types of light.

2. Identify a feature that is visible in only one type of light.

How Light is Used as a Tool

• What do astronomers gain by observing the same object using different types of light?

• How might multi-wavelength observations affect specialization and collaboration in astronomy?

Myths vs Realities

• Handout

• Exploring with Light and Color– Full packet available– Bonnie Eisenhamer– bonnie@stsci.edu