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Learn about the different types of telescopes, their advantages and disadvantages, and the functions they serve. Discover the best viewing conditions for telescopes and explore the various non-optical telescopes used in space exploration.
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Telescopes • Write what is in YELLOW • You will be accountable for text in yellow on quizes.
Where do we put telescopes to have the best viewing conditions? 1. On Earth: CLEAR HIGH DRY COLD DARK
Problem with Telescopes on Earth? Problem: Particles of all sorts in the atmosphere block and cloud the view
2. In Space Solves atmosphere problem – CLEAR VIEW! Examples: Hubble, Cobe , Iras
Problem with telescopes in space? They’re in space! Hard to get to Hard to repair EXPENSIVE!!!
Functions of a Telescope • Collect Light • Magnify Images • Separate Distant Objects • Use as a Camera
I. OPTICAL TELESCOPES(USE VISIBLE LIGHT) Two types: • Refractor – BENDS LIGHT Invented by Hans Lippershey in 1608 Refined by Galileo in 1609
TYPE 1 – REFRACTING TELESCOPE How does it work? • It bends light to create an image • It uses two lenses 1. eyepiece (ocular) lens - small 2. objective lens - large
Type 2 – Reflecting Telescope • Invented by Isaac Newton in 1668 • Uses two mirrors Objective Mirror – Large Secondary (flat) mirror – Small c. Can be VERY LARGE 40 ft - 50 ft diameter objective mirror!
2. Reflector – USES MIRRORS Cheap and common
Most Modern Telescopes combine technologies • Examples • Hubble • Kepler - http://kepler.nasa.gov/
Advantages of a reflector • only one side of the mirror. • (on a refractor the lens has two sides) – cheaper and distortion is less of a problem. • The whole back of the mirror can be supported, therefore can be made very LARGE
II. Non-optical Telescopes • Radio Telescopes a. Location – Earth (atmosphere does not affect radio waves) b. Structure – Large metal dish
c. Size – very large because radio waves have a very long wavelength
d. Arrays – sets of multiple radio telescopes that allow for more data to be gathered.
Ex – VLA (very large array) in Socorro, New Mexico 27 dishes. SETI– Search for Extra-Terrestrial Intelligence looking for intelligent radio signals
Other Non-Optical Telescopes(all are satellites) 2. Infrared – IRAS launched 1983
3. Microwaves – COBE Cosmic Background explorer. Discovered evidence of the Big Bang. Launched 1981