1. Tools for Studying Space

2. Refracting Telescopes
• Uses a lens to bend
or refract light.
• Objective lens produces image by bending light from a distant object so that the light converges
at the focus.

4. Reflecting Telescopes
 Chromatic Aberration
• Light of different colors is focused at different places.
In light optics, wavelengths of higher energy (blue) are bent more strongly & have a shorter focal length.
Reflecting Telescopes
Reflects light off concave mirror,
focusing image in front of the mirror.

6. Viewing Methods  Advantages of Reflecting Telescopes
• Most large optical telescopes are reflectors. Light does not pass through a mirror, so the glass for a reflecting telescope does not have to be of optical quality.
Viewing Methods

7. NASA IR Telescope, Mauna Kea
 Properties of Optical Telescopes
• 3 important properties of refracting & reflecting telescopes:
1. Light-gathering power
2. Resolving power
3. Magnifying power
NASA IR Telescope, Mauna Kea

8. Arecibo Detecting Invisible Radiation
Radio Telescopes - makes observations in radio wavelengths.
 Advantages of Radio Telescopes
• Less affected by turbulence in the atm., clouds & weather.
• No protective dome required, reduces the cost.
• Can “see” through interstellar dust clouds that obscure visible wavelengths.
Arecibo

9. Space Telescopes  Produce clearer images than Earth-based telescopes.
 Hubble Space Telescope
• 1st space telescope, built by NASA. Put into orbit around Earth in April 1990.
Video

12.  Other Space Telescopes
• To study X-rays, NASA uses Chandra X-Ray Observatory. Launched in 1999.
• Compton Gamma-Ray Observatory, was used to study both visible light & gamma rays.
• James Webb Space Telescope studies infrared radiation.
James Webb
Chandra X-ray
Compton Gamma Ray