Telescopes
Telescope An instrument that collects electromagnetic radiation from objects in space Concentrates the electromagnetic radiation for better observation
Optical Telescopes Most common type of telescope Used to study visible light from objects in universe Enables you to see millions of stars
Refracting Telescopes Use lenses to gather and focus light
Two Disadvantages of Refracting Telescopes 1. Images cannot be perfectly focused 2. Size of objective lens limits the size of the telescope
Reflecting Telescopes Use a curved mirror & a flat mirror to gather & focus light
Three Advantages of Reflecting Telescopes 1. Large mirrors can gather more light. 2. Flaws in the mirror’s glass do not affect the light. 3. Mirrors can focus all colors of light at the same time.
Optical Telescopes & Atmosphere Air above telescope makes starlight shimmer & blur. Light pollution affects ability to see dim objects.
Placement of Telescopes Dry environments Mountaintops Less light pollution Less air pollution Air is thinner Space
Electromagnetic Spectrum
Detecting Electromagnetic Radiation EM spectrum = all of the wavelengths of electromagnetic radiation Each color of light is a different wave- length. Humans can see radiation from red light (long wave) to blue light (shorter wave).
Nonoptical Telescopes Used to study invisible radiation Each type of EM radiation gives different clues about objects
Detecting Electromagnetic Radiation Visible light is small part of EM spectrum. Most of EM spectrum is invisible Radio waves (longest waves) Microwaves Infrared waves Ultraviolet wav es X-rays Gamma waves (shortest waves)
Radio Telescopes Detect radio waves Can be linked with other radio telescopes Surface does not have to be solid Must be much larger than optical telescopes Radio waves can be as large as a building
Radio Telescope & VLA
Nonoptical Telescopes in Space Placed in space because most EM radiation is blocked by Earth’s atmosphere