Sky Show.Get ready for this autumn's aerial eye candy--aurora borealis, the mysterious northern lights. Don't freak out freak out Substance abuse A verb, popularized in the US in the '60s–to experience nightmarish hallucinations including by LSD or a similar drug. See 'Bad trip.', Flashback. if one night this fall the sky over your backyard morphs into a dazzling light show. It's no alien invasion--it's an awesome display called the aurora borealis, or northern lights. Usually you'll spot these multicolored displays near the North Pole (see map). But this autumn, due to a natural burst in solar activity, auroras may appear much farther south than usual--maybe even as far south as Florida and Mexico. To get a front row seat for these amazing auroras, gaze skyward sky·ward adv. & adj. At or toward the sky. sky  wards adv. from dusk until midnight. Auroras shimmer and glow when high-speed particles from the sun collide with gases in Earth's atmosphere. They can last from a few minutes to a few days. But you'll need a clear moonless night to catch them. So if you live in a big city, plan an overnight field trip to the country for a show that's out of this world. SUN BURST Auroras are "born" some 150 million kilometers (93 million miles) away in the solar system's largest ball of scorching scorch v. scorched, scorch·ing, scorch·es v.tr. 1. To burn superficially so as to discolor or damage the texture of. See Synonyms at burn1. 2. gas our sun. During the average year, the, sun is a fiery furnace with occasional explosions on the surface. That's because the Still continuously ejects plasma, a seething seethe intr.v. seethed, seeth·ing, seethes 1. To churn and foam as if boiling. 2. a. To be in a state of turmoil or ferment: gaseous mixture of atomic particles--electrons, protons, and ions. Streams of plasma called solar winds blast through space in all directions at speeds of about 400 km (250 mi) per second. But right now the solar surface has gone ballistic. The sun is approaching a solar maximum, a peak in its 11-year activity cycle, explains Richard Vondrak, chief physicist at NASA's Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately 6.5 miles northeast of Washington, D.C. in Greenbelt, Md. So far scientists aren't sure what causes these solar weather cycles. Researchers measure "solar max" by observing an increase in sunspots sunspots, dark, usually irregularly shaped spots on the sun's surface that are actually solar magnetic storms. The Chinese recorded dark features on the sun seen with the naked eye in 28 B.C. , splotches of gas on the sun's surface that appear darker because they're cooler. Sunspots trigger solar flares, massive eruptions that hurl tremendous amounts of radiation (energy waves) space. Some solar flares pack as much punch as a 2-billion-megaton bomb! But not to worry. The explosive power won't reach Earth. You'll just be treated to the best sky show this decade. WHY AURORAS FORM The formation of auroras depends on solar winds reaching Earth. Gusting past Mercury and Venus the two planets closest to the sun), solar winds take two or three days to reach our planet--the third closest. Fortunately, the hot plasma doesn't slam into Earth with a cataclysmic cat·a·clysm n. 1. A violent upheaval that causes great destruction or brings about a fundamental change. 2. A violent and sudden change in the earth's crust. 3. A devastating flood. blow. About 65,000 km (40,400 mi) above the surface, solar winds collide with Earth's magnetic field Earth's magnetic field (and the surface magnetic field) is approximately a magnetic dipole, with one pole near the north pole (see Magnetic North Pole) and the other near the geographic south pole (see Magnetic South Pole). , an invisible region of magnetic forces surrounding the planet. The field deflects solar winds like a giant shield. As the winds blow past the planet, they temporarily distort and weaken the bubble-shaped magnetosphere magnetosphere: see Van Allen radiation belts. magnetosphere Region around a planet (such as Earth) or a natural satellite that possesses a magnetic field (see (space region containing Earth's magnetic field) on the "night" side of the globe. When solar winds are strong enough, some plasma leaks into the weakened magnetosphere. As the plasma circulates within the magnetosphere, it generates one key ingredient for aurora formation: high-energy electrons (negatively charged particles). Some of these particles stream down Earth's magnetic field lines into two large oval regions near Earth's poles. From space, these regions look like halos of light, about 4,000 km (2,500 mi) in diameter, glowing above Earth. The halos are called "auroral ovals." COLOR BLAST What gives aurora's their vibrant colors? Within auroral ovals, some 100 to 1,000 km (62 to 620 mi) over our heads, high-energy electrons from solar plasma collide with air molecules in Earth's upper atmosphere. Each type of atom or molecule produces its own color palette. (A similar process is at work in TV screens: An electron gun fires a beam into various metals embedded in the screen, which combine to produce a color picture.) When a high-energy electron bumps into an atom of oxygen, the oxygen becomes "excited." If the oxygen atom can hold onto that energy for a fraction of a second, it gives off green or red light. Overlapping reds and greens produce a yellowish glow. Electrons colliding with atomic nitrogen may paint the sky pink, blue or purple (though these colors are difficult for the human eye to detect). When billions of atoms sparkle together, it's show time! For more information on auroras, check out these websites! National Aeronautics and Space Administration National Aeronautics and Space Administration (NASA), civilian agency of the U.S. federal government with the mission of conducting research and developing operational programs in the areas of space exploration, artificial satellites (see satellite, artificial), : www.spaceweather.com www.sunspotcycle.com National Oceanic and Atmospheric Administration Noun 1. National Oceanic and Atmospheric Administration - an agency in the Department of Commerce that maps the oceans and conserves their living resources; predicts changes to the earth's environment; provides weather reports and forecasts floods and hurricanes and : www.sel.noaa.gov/pmap University of Alaska Geophysical Institute: www.gi.alaska.edu COLORFUL LIGHTS Although sunlight appears white, it's composed of various colors jointly known as the visible spectrum--red, orange, yellow, green, blue, indigo, and violet. Did you know that each color light has different properties? YOU NEED: Dark room with white wall * flashlight * clear cup * water * straw * skim milk skim milk n. The milk from which the cream has been removed. skim milk the residue from whole milk after the cream has been skimmed off. In today's usage it is the residue after the butterfat is removed. TO DO 1. Place cup of water 30 cm (1 ft) from wall. 2. Place flashlight so it shines through water onto wall. Note color of light on wall. 3. Dip straw into milk. Drop 2.5 cm (1 in.) of milk into water and stir slowly. Does the light spot change color? 4. Repeat step 3 until color gets richer. Conclusions How does the color of light change? Why do some color travel through clear water as opposed to murky water? [ILLUSTRATION OMITTED] Cross-Curricular Connection Geography: Have students identify the range of aurora borealis on a map. Did You Know? * English astronomer Richard Carrington was the first to link solar activity and auroras in 1859 when he observed a solar flare--and two nights later witnessed massive auroras. * Auroras are named for the Roman goddess of dawn, who opened the gates of heaven for the sun god Apollo every morning. * In March 1989, electric currents associated with a brilliant aurora knocked out power in a Canadian hydroelectric plant, causing a widespread blackout. National Science Education Standards The National Science Education Standards (NSES) are a set of guidelines for the science education in primary and secondary schools in the United States, as established by the National Research Council in 1996. Grades 5-8: Earth in the solar system * structure and function in living systems * motion and forces Grades 9-12: energy in Earth's system * structure and properties of matter * motion and forces o interactions of energy and matter Resources "Anatomy of an Aurora," and "An Aurora Watcher's Guide," Sky & Telescope, March 2000, p. 35. "Earth, Wind and Fireworks fireworks: see pyrotechnics. fireworks Explosives or combustibles used for display. Of ancient Chinese origin, fireworks evidently developed out of military rockets and explosive missiles and accompanied the spread of military explosives westward to ," The New York New York, state, United States New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of Times, March 28, 2000, p. Fl. Auroras: Light Shows in the Night Sky, by Donna Walsh Shepherd (Franklin Watts, 1995) Aurora forecast: NASA NASA: see National Aeronautics and Space Administration. NASA in full National Aeronautics and Space Administration Independent U.S. : www.spaceweather.com and www.sunspotcycle.com |
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