1. Telescopes and the Electromagnetic Spectrum Section 3

2. Optical Astronomy Optical telescope
Collects visible light for closer observation
2 lenses
Objective lens: collects light and forms an image at the back of the telescope
Eyepiece: magnifies the images from the objective lens

3. Without an optical telescope you can see about 6,000 stars
With an optical telescope you can see millions of stars

5. Refracting Telescopes
Use a set of lenses
Curved objective lens bends light and focuses it to the eyepiece
Eyepiece lens magnifies the image
Disadvantage: if the curved lens is too large the glass will sag and distort the image

7. Reflecting Telescopes
Use curved mirrors
Large curved mirror reflects light to a focal point
The focal point reflects light to the eyepiece
Advantages:
Mirrors can be made very large
Mirrors are polished on one side to prevent flaws from glass
Mirrors reflect light of all colors to the same place

8. What do you think would be an advantage to having a telescope in space compared to one on the ground?

10. Electromagnetic Spectrum
Made of all the wavelengths of electromagnetic radiation
Visible light is only a small portion
Earth’s atmosphere allows these in….
Infrared, visible light, some ultraviolet, and radio
Earth’s atmosphere blocks….
Gamma, X rays, some ultraviolet
Astronomers can detect….
Visible light, infrared, and radio waves