Electromagnetic Spectrum Low Energy High Energy Low Frequency High Frequency High Wavelength Low Wavelength Radio Waves low energy, low frequency, high wavelength Can be heard by elephants Sound made by Earth as it hums may be from storms AM waves bounce off ionosphere (part of our atmosphere) so they can be heard far away from the transmitter FM waves dont bounce so the signal weakens with distance from the transmitter Microwave The longer microwaves are the ones that heat our food in a microwave oven. Microwaves excite the water molecules in food. The heated water cooks the food. If you had a sensitive microwave telescope in your house, you would detect a faint signal leaking out of your microwave oven! Microwave ovens are shielded to protect you from overexposure. Microwaves are good for transmitting information because they can penetrate haze, light rain and snow, clouds, and smoke. Shorter microwaves are used for Doppler radar used in weather forecasts. One microwave can carry 1000 telephone calls. What is Radar? Radar stands for "radio detection and ranging. Radar was developed to detect objects and determine their range (or position) by transmitting short bursts of microwaves. Terahertz astronomers image gas and dust between stars with them because they exist at low temperatures in space very little enters our atmosphere so use telescopes at high altitudes or in space to monitor this type of radiation might be useful for high altitude communications future use to transfer data 1000 faster than with microwaves! Terahertz can see through clothing, paper, wood, plastic and other nonmetallic materials without harmful exposure Full Body Scan technology used by Homeland Security for airport screening at security check points and to inspect packages can see through paint so might be used to uncover and preserve historic art work and murals might detect cancer and cavities in teeth Terahertz Rays are generated when tape is removed. Discovered in 1709 when Herschel laid a thermometer next to a rainbow. The thermometer got hot! We experience infrared as heat energy. "Near infrared" waves are shorter while "far infrared" are longer (closer to microwave portion of the spectrum). INFRARED Far Infrared We experience far infrared as heat! These waves are used to warm fast food, grill in new backyard barbecues, and in heat seeking missiles. Some snakes see infrared. We need night vision goggles! This is a picture of a cat in infrared. The orange areas are the warmest and the white-blue areas are the coldest. This picture shows a man holding up a lighted match! The Earth, the Sun, and far away things like stars and galaxies also give off infrared. Near Infrared Near infrared waves are not hot at all - in fact you cannot even feel them. They are used by your TV's remote control. New guitars use IR pickups to eliminate electric hum. Oximeters measure the amount of oxygen in blood. The oximeter compares how much red light and infra red light is absorbed by the blood. Oxygenated blood absorbs light at 660nm (red light), whereas deoxygenated blood absorbs light at 940nm (infra-red). The relative absorption of each type of is used to calculate the oxygen saturation level of the blood. Near Infrared radiation is also used to image the internal structures of the sinuses during surgery. This reduces exposure to radiation during CT scans and reduces the risk of injury to the brain and eyes during surgery. Spitzer Space Telescope Uses infrared to look at star formation, centers of galaxies, newly forming planetary systems, and cooler objects in space. The telescope must be cooled to near absolute zero (-459 degrees Fahrenheit or -273 degrees Celsius) to work. Spitzer is the 4 th and last in NASAs Great Observatories Program. Visible Light Roy G. Biv Ultraviolet We learn about stars and galaxies by studying the ultraviolet radiation they give off. Hubble Space Telescope Hubble observes stars and galaxies in near ultraviolet. It is one of NASAs Great Observatories. Photo of the Sun in Extreme Ultraviolet Sunburn While most ultraviolet waves from the Sun are blocked by Earth's atmosphere, some get through. Scientists developed a UV index to help people protect themselves. UV IndexCategorySunburn Time over 9extreme less than 15 minutes 7-9highabout 20 minutes 4-7mediumabout 30 minutes 0-4lowmore than 1 hour Uses for Ultraviolet Kill germs in goggle cabinet Detect scratches on cornea of eye Identify counterfeit money Make cloth bright Glow in the dark posters Identify minerals By some insects to see What we see.What a bee sees. X RAYS X rays go through our skin but cast shadows of our bones onto film. Because their wavelengths are so small, we talk about x-rays as photons. X rays are dangerous! The Foot-O-Scope was invented in the 1920s and used up until the 1960s for shoe fitting. It gave off too much X-ray! Engineering Disasters https://www.youtube.com/watch?v= wbMN6jueU1A https://www.youtube.com/watch? v=QVlEXd9w7vk In space, black holes, neutron stars, binary star systems, supernova remnants, stars, the Sun, and even some comets emit X-rays. This is a picture of our Sun in x-ray. Chandra X-Ray Observatory One of NASAs Great Observatories, Chandra has been in space since 1999. NuStar launched June 13, 2012 uses X-rays to study black holes, active galaxies, and supernova remnants 11 th mission in NASAs Small Explorer program Image of the black hole in the center of our Milky Way Galaxy. Gamma Rays produced by supernova explosions, the destruction of atoms, and the decay of radioactive material supernova explosions, neutron stars, pulsars, and black holes are all sources of gamma-rays can kill living cells (gamma rays cause cancer and can also be used to kill cancer) travel to us across the universe and are absorbed blocked! - by the Earth's atmosphere Compton Gamma Ray Observatory CGRO satellite being deployed from the Space Shuttle orbiter in NASAs Great Observatory satellite worked until 2000 when it was deorbited. Uses for Gamma Rays find cracks in airplane wings and in nuclear power plant piping fight cancer Danger from Gamma Rays on Earth meltdown of nuclear reactor in Ukraine meltdown of nuclear reactor in Japan radon gas build up in NJ homes Gamma Rays NJs Oldest Rocks During radioactive decay, uranium decays to lead. The Sensitive High Resolution Ion Microprobe (SHRIMP) is a device that determines the age of rock by measuring its lead and uranium content. This is known as geochronology. SHRIMP has dated some of the oldest rocks and crystals ever found - 4 billion years old! 2009 Gamma Knife in use at Robert Wood Johnson Hospital in New Brunswick to treat brain and spinal tumors. The Gamma Knife uses radiation in an approach known as radiosurgery. Each radiation beam is too weak to damage normal tissue but when focused precisely on the target, the radiation is sufficient to treat the affected area. The radiation source used is called cobalt 60. Hospital Equipment Many machines and treatments contain radioactive substances. These must be disposed of properly to keep radiation levels from building up above safe levels. NJs Greensand Marl Geiger Counter DANGER From Space! Gamma-ray bursts can release more energy in 10 seconds than the Sun will emit in its entire 10 billion-year lifetime! So far, all bursts observed have come from outside our Milky Way Galaxy. Eventually, a gamma-ray burst will occur in the Milky Way. Life on Earth will end if the planet is hit by a gamma ray burst. Swift was launched in On April 13, 2010 its burst-o-meter recorded its 500th gamma ray burst. The Milky Way Galaxy as Seen in Different Wavelengths Multiwavelength Milky Way Images