What Channel is That?

 Visible light is a form of electromagnetic radiation.  Others include:  Radio waves  Infrared waves (heat)  Ultraviolet waves  X-rays  Gamma rays  Radio Astronomy:  Use of radio waves to learn about composition of stars

 Are a very important type of EMR in our daily lives!  Objects in the universe also emit radio waves.  Radio telescopes capture radio waves emitted by radio objects.  they allow scientists to “see” objects never seen before because radio waves penetrate through dust particles where visible light cannot. ▪ Computers are hooked up to radio receivers that convert the radio waves into a colour picture for us to see.

 Interferometry:  Methods of connecting two radio telescopes together to produce one large telescope (like light telescopes) ▪ Example: Very Large Array (VLA) in New Mexico ▪ Very long baseline interferometry (VLBI) ▪ Uses computers to connect as many radio telescopes as they want together to produce an image.  Images can be seen up to 100X in detail

 There is a radio dish in space  Allows scientists to make a telescope twice Earth’s diameter, ▪ They can image objects over 13 billion light years from Earth!

 Built the first radio antenna  Discovered radio waves that were interfering with telephone calls were coming from space!

 Radio waves are recorded and graphed  Today, computers incorporate color for signal strength

 Astronomical Unit (AU): is the distance from Earth to the Sun (150 million km)  1 light year = 9,460,800,000,000 km = 63,240 AU  Astronomers measure astronomical distances in light years – how far light can travel in one year.

 Make an Electromagnetic Spectrum!  Include:  All types of EMR  One fact about each type  Wavelengths (diagram and numbers)  Frequency (numbers)