The Classroom Activities Electromagnetic This poster contains three classroom activities designed to introduce middle and high school students (grades 6–12) to different portions of the Spectrum electromagnetic spectrum, including those used by Origins missions. Suggested science standards, Overview vocabulary, and science background information are provided to facilitate lesson planning. The activities can be done separately or together. The light that we see with our eyes – visible In astronomy, scientists use the properties light – represents only a small portion of the of light to learn about celestial objects that The Visible Spectrum provides instructions electromagnetic spectrum. Developing the tech- are too far away to visit. Each portion of the for creating a visible spectrum with an overhead nology to detect and use other portions of the electromagnetic spectrum provides unique projector. Introduce the electromagnetic spectrum electromagnetic spectrum – the “invisible” light clues about the nature of our universe. The by showing students that white light is composed that our eyes cannot see – has had a tremendous missions and research programs in NASA’s of a rainbow of colors. Students can draw the impact on our daily lives. When you listen to a Astronomical Search for Origins program visible spectrum and explore how common objects radio, heat your food in a microwave oven, use a use innovative technologies to observe the “filter” light. Use these activities to engage students’ remote control, or have an X-ray taken, you are universe at a variety of wavelengths (ultra- interest in electromagnetic energy. using “invisible” light. violet, visible, and infrared) in search of the answers to two enduring human questions: The Herschel Infrared Experiment Where did we come from? helps students to expand their knowledge of the electromagnetic spectrum. Students will discover Are we alone? the “invisible” light that lies just beyond the red end of the visible spectrum – infrared light. Use this as an outdoor class laboratory activity, a student learning station, a demonstration, or as Vocabulary part of a science fair project. Electromagnetic energy: A form of energy that travels through space as vibrations of electric and Invisible Light Sources and Detectors magnetic fields; also called radiation or light. gives students direct experience with radio, infrared, visible, and ultraviolet waves. Students will identify Frequency: Describes the number of wave crests passing by a fixed point in a given time period sources of visible and “invisible” forms of light in (usually one second). Frequency is measured in hertz (Hz). our everyday lives, and identify ways to detect and to block these types of light. Teachers can use these Spiral galaxy: A large pinwheel-shaped system of stars, dust, and gas clouds. concepts to discuss how we protect ourselves from harmful forms of light. Wave: A vibration in a medium or in space that transfers energy from one place to another. Sound waves are vibrations of air. Light waves are vibrations of electric and magnetic fields. Visit the NASA Space Science Education Resource Directory (http://teachspacescience.org) or the http://origins. Wavelength: The distance between two wave crests, which is the same as the distance between Origins Education Forum website ( stsci.edu) to find additional education resources two troughs. developed by NASA’s Origins missions and programs. Background Information 1. What is the electromagnetic spectrum? 4. Why do we put telescopes in space? The electromagnetic spectrum consists of all the Astronomers put telescopes in space to study Each image provides important clues about the different wavelengths of electromagnetic energy, electromagnetic energy that does not reach the properties of this system. The visible-light image including radio waves, microwaves, infrared light, visible Earth’s surface. Each type of electromagnetic energy shows sweeping spiral arms, clusters of young light, ultraviolet light, X-rays, and gamma rays. The provides important clues about the properties of stars, and clouds of molecular gas and dust. Young only region in the entire electromagnetic spectrum that celestial objects. We also put telescopes in space to stars dominate the appearance of the ultraviolet our eyes can detect is the visible region. Although the study visible light, even though visible light passes image, which provides a unique view of the spiral wavelength ranges for forms of light other than visible through the Earth’s atmosphere. Turbulence in our structure. The X-ray image shows clouds of multi- are not precisely defined, typical wavelength ranges are atmosphere blurs the images that scientists obtain million-degree gas and point-like objects associated as follows: gamma rays, less than 0.001 nanometers; with telescopes on the ground. By placing telescopes with black holes and neutron stars. Longer infrared X-rays, 0.001 to 10 nanometers; ultraviolet light, 10 to in space, above the Earth’s atmosphere, scientists can wavelengths track warm dust heated by recent star 400 nanometers; visible light, 400 to 700 nanometers; obtain a much sharper view of the universe. formation. The radio image maps the locations infrared light, 700 nanometers to 1 millimeter; and of star-forming regions and supernova remnants radio waves, longer than 1 millimeter. The shortest 5. How do we detect “invisible” forms produced by the deaths of massive stars. radio waves (wavelengths between 1 millimeter and of light? about 30 centimeters) are also referred to as microwaves. 7. How do scientists use the (One nanometer equals one-billionth of a meter.) Scientists build electronic devices that are sensitive electromagnetic spectrum to to the light our eyes cannot see. Then, so that we learn about the universe? can visualize these regions of the electromagnetic 2. What is the relationship between spectrum, computer image-processing techniques The images of the Whirlpool Galaxy on the front wavelength, frequency, and energy? translate the “invisible” light into pictures that we of the poster show how combining information The speed of light equals the frequency times the can see. from each region of the electromagnetic spectrum wavelength. This means that the frequency is equal to leads to a more complete understanding of a the speed of light divided by the wavelength. Because 6. What are the different images of the celestial object. In addition to taking images all electromagnetic waves travel at the same speed Whirlpool Galaxy on the front of the of celestial objects, scientists also use devices (300,000,000 meters per second) in the vacuum of poster? called spectrographs to disperse, or separate, the empty space, the shorter the wavelength is, the higher light from celestial objects into its component the frequency. The energy of a wave is directly pro- The upper image, which was obtained by the wavelengths. Features in the resulting spectrum portional to its frequency, but inversely proportional to Hubble Space Telescope, is a visible-light image of help astronomers to measure an object’s properties, its wavelength. In other words, the greater the energy, the Whirlpool Galaxy. This detailed image helps such as its temperature, composition, density, and the larger the frequency and the shorter (smaller) the astronomers to study the structure and star-forming motion. wavelength. Short wavelengths are more energetic than processes of this spiral galaxy. long wavelengths. Scientists in NASA’s Astronomical Search for The visible-light image in the lower portion of Origins program will image stars and galaxies the poster shows a wider view of the same Hubble 3. Do all types of electromagnetic energy at ultraviolet, visible, and infrared wavelengths. Space Telescope image, revealing a smaller, nearby reach the Earth’s surface? We will also look for characteristic patterns of companion galaxy. Four additional images, obtained light, or spectral “fingerprints,” emitted by atoms Our atmosphere blocks out harmful energy like X-rays, with various space-based and ground-based and molecules to measure elements in the early gamma rays and most ultraviolet rays. It also blocks out telescopes, measure the “invisible” light emitted by universe and to search for signatures of life. most infrared energy, as well as very low energy radio the two galaxies. To visualize the “invisible” light, Combining the light from multiple telescopes waves. Visible light, most radio waves, some ultraviolet scientists have used computer image-processing will allow us to achieve the capabilities needed rays, small wavelength ranges of infrared light, and techniques to translate the various electromagnetic to identify and study terrestrial planets orbiting some microwaves pass through the atmosphere. energies into pictures we can see. nearby stars. The Visible To use an overhead projector, place two pieces of 8-inch spectrum appears to have boundaries. Asking if by 10-inch dark paper on the projector to create a “slit” there is anything beyond the red and violet ends of Spectrum about 2.5 centimeters (1 inch) wide on the base plate the spectrum introduces the notion of “non-visible” of the projector. Turn on the projector lamp and focus electromagnetic energy. Human skin is sensitive Target Grade Levels: 6–12 the “slit” on a white wall or screen. Place the diffraction to the ultraviolet energy beyond the violet light; grating (about 4 or 5 inches square) in front of the upper it sunburns. And, skin senses the infrared energy