 Students will be able to define electromagnetic radiation.  Students will be able to explain how telescopes work.  Students will be able to describe how space exploration helps scientists learn about the universe.

 Refraction: Occurs when a light ray changes direction as it passes from one material into another.

 Page 764  Main Idea: Radiation emitted or reflected by distant objects allows scientists to study the universe.

 Page 764  Electromagnetic Radiation: Electric and magnetic disturbances traveling through space as waves.  Electromagnetic Spectrum: Electromagnetic radiation arranged according to wavelength and frequency.

Electromagnetic Spectrum High Energy = Hot Low Energy = Cool

 Page 764  Wavelength and Frequency: Wavelength: Distance between peaks on a wave. Frequency: Number of waves that pass a given point pre second. Measured in Hertz (Hz) = 1 cycle per second.

 Page 765  Telescopes: Objects in space emit electromagnetic radiation. Telescopes collect electromagnetic radiation and turn it into an image. Aperture: A telescope’s opening. Can be up to 10 m in diameter.  Larger aperture = More electromagnetic radiation.

 Page 766  Refracting and Reflecting Telescopes: Refracting Telescope: Uses lenses to bring visible light into a focus.  Invented in 1600s. Reflecting Telescopes: Invented in Uses mirrors to bring visible light into focus. Best locations for telescopes are away from city lights and at high elevations where there is less atmosphere to interfere with images.

 Page 766  Telescopes Using Non-Visible Wavelengths: Some electromagnetic radiation cannot be seen.  i.e. X-Rays and Gamma Rays Telescopes can only detect the direction from which this type of radiation comes.

 Page 766  Radiotelescope: Uses a dish to collect radio and longer wave length electromagnetic radiation.  Interferometry: Technique that combines several images to create 1 image. Brings out more details.