Tools for Studying Space. © 2011 Pearson Education, Inc. Telescopes.
34
Tools for Studying Space
-
Upload
alisha-rogers -
Category
Documents
-
view
218 -
download
0
Transcript of Tools for Studying Space. © 2011 Pearson Education, Inc. Telescopes.
Tools for Studying Space
© 2011 Pearson Education, Inc.
Telescopes
An overview of telescopes
• http://www.neok12.com/php/watch.php?v=zX5f016756667557795f557b&t=Telescope
Properties of Optical telescopes
1. Light gathering power (more light)
2. resolving power (sharpness)
3. magnifying power (increased size)
Bill Nye on Refraction and Reflection
http://www.teachertube.com/viewVideo.php?video_id=107400
Refracting and Reflecting telescopes
Objective Lens makes an imageby bending light from a distant object so the light converges on a focusGalileoChromatic aberration-different wavelengths of light bend differently and appear fuzzy
Uses a concave mirror that focuses the light in front of the mirror
Newton
© 2011 Pearson Education, Inc.
Refracting lens
Optical Telescopes
© 2011 Pearson Education, Inc.
Images can be formed through reflection or refraction
Reflecting mirror
Optical Telescopes
© 2011 Pearson Education, Inc.
Why are most Modern telescopes are all reflectors? Discuss at your table and come up with one:
• Light traveling through lens is refracted differently depending on wavelength
• Some light traveling through lens is absorbed
• Large lens can be very heavy, and can only be supported at edge
• A lens needs two optically acceptable surfaces; mirror needs only one
Optical Telescopes
© 2011 Pearson Education, Inc.
5.1 Optical Telescopes
The Keck telescope, a modern research telescope
Space Telescopes
Orbit above the earth’s atmosphere and produce clearer images
Hubble was the first built by NASA
Others are the Chandra X-ray and Compton Gamma ray
© 2011 Pearson Education, Inc.
The Hubble Space Telescope
The Hubble Space Telescope has a variety of detectors
© 2011 Pearson Education, Inc.
The Hubble Space Telescope
The Hubble Space Telescope’s main mirror is 2.4 m in diameter and is designed for visible, infrared, and ultraviolet radiation
© 2011 Pearson Education, Inc.
The Hubble Space Telescope
Here we compare the best ground-based image of M100, on the left, with the Hubble images on the right
© 2011 Pearson Education, Inc.
Light-gathering power: Improves detail
Brightness proportional to square of radius of mirror
Photo (b) was taken with a telescope twice the size of the telescope that took photo (a)
Telescope Size
© 2011 Pearson Education, Inc.
Resolving power: When better, can distinguish objects that are closer together
Resolution is inversely proportional to telescope size—bigger is better!
Telescope Size
© 2011 Pearson Education, Inc.
Effect of improving resolution:
(a) 10′; (b) 1′; (c) 5″; (d) 1″
5.2 Telescope Size
© 2011 Pearson Education, Inc.
Atmospheric blurring is due to air movements
High-Resolution Astronomy
© 2011 Pearson Education, Inc.
Solutions:
• Put telescopes on mountaintops, especially in deserts
• Put telescopes in space
High-Resolution Astronomy
© 2011 Pearson Education, Inc.
Radio telescopes
• Similar to optical reflecting telescopes
• Prime focus
• Less sensitive to imperfections (due to longer wavelength); can be made very large
Radio Astronomy
© 2011 Pearson Education, Inc.
Largest radio telescope is the 300-m dish at Arecibo
5.5 Radio Astronomy
© 2011 Pearson Education, Inc.
Longer wavelength means poor angular resolution
Turn to your table and discuss some advantages of radio astronomy:
• Can observe 24 hours a day• Clouds, rain, and snow don’t interfere
• Observations at an entirely different frequency; get totally different information
Radio Astronomy
About telescopes
• http://www.youtube.com/watch?v=sAlrKptnD4Q
© 2011 Pearson Education, Inc.
Interferometry:
• Combines information from several widely spread radio telescopes as if it came from a single dish
• Resolution will be that of dish whose diameter = largest separation between dishes
Interferometry
© 2011 Pearson Education, Inc.
Infrared radiation can produce an image where visible radiation is blocked; generally can use optical telescope mirrors and lenses
Space-Based Astronomy
© 2011 Pearson Education, Inc.
Infrared telescopes can also be in space; the image on the top is from the Infrared Astronomy Satellite
Space-Based Astronomy
© 2011 Pearson Education, Inc.
The Spitzer Space Telescope, an infrared telescope, is in orbit around the Sun. These are some of its images.
Space-Based Astronomy
© 2011 Pearson Education, Inc.
Ultraviolet observing must be done in space, as the atmosphere absorbs almost all ultraviolet rays.
Space-Based Astronomy
© 2011 Pearson Education, Inc.
X rays and gamma rays will not reflect off mirrors as other wavelengths do; need new techniques
X rays will reflect at a very shallow angle and can therefore be focused
Space-Based Astronomy
© 2011 Pearson Education, Inc.
X-ray image of supernova remnant
Space-Based Astronomy
© 2011 Pearson Education, Inc.
Gamma rays cannot be focused at all; images are therefore coarse
Space-Based Astronomy
© 2011 Pearson Education, Inc.
Much can be learned from observing the same astronomical object at many wavelengths. Here is the Milky Way.
Full-Spectrum Coverage
