Northern Lights or Aurora Borealis Explained What are Northern Lights? The bright dancing lights of the aurora are actually collisions between electrically charged particles from the sun that enter the earth's atmosphere. The lights are seen above the magnetic poles of the northern and southern hemispheres. They are known as 'Aurora borealis' in the north and 'Aurora australis' in the south.. Auroral displays appear in many colours although pale green and pink are the most common. Shades of red, yellow, green, blue, and violet have been reported. The lights appear in many forms from patches or scattered clouds of light to streamers, arcs, rippling curtains or shooting rays that light up the sky with an eerie glow. What causes the Northern Lights? The Northern Lights are actually the result of collisions between gaseous particles in the Earth's atmosphere with charged particles released from the sun's atmosphere. Variations in colour are due to the type of gas particles that are colliding. The most common auroral color, a pale yellowish-green, is produced by oxygen molecules located about 60 miles above the earth.

Rare, all-red auroras are produced by high-altitude oxygen, at heights of up to 200 miles. Nitrogen produces blue or purplish-red aurora. The connection between the Northern Lights and sunspot activity has been suspected since about 1880. Thanks to research conducted since the 1950's, we now know that electrons and protons from the sun are blown towards the earth on the 'solar wind'. (Note: 1957-58 was International Geophysical Year and the atmosphere was studied extensively with balloons, radar, rockets and satellites. Rocket research is still conducted by scientists at Poker Flats, a facility under the direction of the University of Alaska at Fairbanks - see web page The temperature above the surface of the sun is millions of degrees Celsius. At this temperature, collisions between gas molecules are frequent and explosive. Free electrons and protons are thrown from the sun's atmosphere by the rotation of the sun and escape through holes in the magnetic field. Blown towards the earth by the solar wind, the charged particles are largely deflected by the earth's magnetic field.

However, the earth's magnetic field is weaker at either pole and therefore some particles enter the earth's atmosphere and collide with gas particles. These collisions emit light that we perceive as the dancing lights of the north (and the south). The lights of the Aurora generally extend from 80 kilometres (50 miles) to as high as 640 kilometres (400 miles) above the earth's surface. Where is the best place to watch the Northern Lights? Northern Lights can be seen in the northern or southern hemisphere, in an irregularly shaped oval centred over each magnetic pole. The lights are known as 'Aurora borealis' in the north and 'Aurora australis' in the south. Scientists have learned that in most instances northern and southern auroras are mirror-like images that occur at the same time, with similar shapes and colors. Because the phenomena occurs near the magnetic poles, northern lights have been seen as far south as New Orleans in the western hemisphere, while similar locations in the east never experience the mysterious lights. However the best places to watch the lights (in North America) are in the northwestern parts of Canada, particularly the Yukon, Nunavut, Northwest Territories and Alaska.

Auroral displays can also be seen over the southern tip of Greenland and Iceland, the northern coast of Norway and over the coastal waters north of Siberia. Southern auroras are not often seen as they are concentrated in a ring around Antarctica and the southern Indian Ocean. Areas that are not subject to 'light pollution' are the best places to watch for the lights. Areas in the north, in smaller communities, tend to be best. When is the best time to watch for auroral displays? Researchers have also discovered that auroral activity is cyclic, peaking roughly every 11 years. The next peak period is 2013. Winter in the north is generally a good season to view lights. The long periods of darkness and the frequency of clear nights provide many good opportunities to watch the auroral displays. Usually the best time of night (on clear nights) to watch for auroral displays is local midnight (adjust for differences caused by daylight savings time). Legends of the Lights 'Aurora borealis', the lights of the northern hemisphere, means 'dawn of the north'. 'Aurora australis' means 'dawn of the south'. In Roman myths, Aurora was the goddess of the dawn.

\par Many cultural groups have legends about the lights. In medieval times, the occurrences of auroral displays were seen as harbingers of war or famine. The Maori of New Zealand shared a belief with many northern people of Europe and North America that the lights were reflections from torches or campfires. The Menominee Indians of Wisconsin believed that the lights indicated the location of manabai'wok (giants) who were the spirits of great hunters and fishermen. The Inuit of Alaska believed that the lights were the spirits of the animals they hunted: the seals, salmon, deer and beluga whales. Other aboriginal peoples believed that the lights were the spirits of their people. Aurora Name Meaning & Origin | Baby Name Wizard Aurora Name Meaning & Origin Facebook Twitter Google+ Email Origin of the name Aurora: Derived from the Latin aurora (dawn). The name was borne by the Roman mythological goddess of dawn and by the princess in the popular fairy tale Sleeping Beauty. From A World of Baby Names by Teresa Norman. Related Names: US Popularity of Aurora Over Time Sister & Brother Names Know an Aurora? What are her siblings named?

Enter Sibling Name F Age Report inappropriate content Comments and insights on the name Aurora: | Edit I knew a beautiful artistic woman named Aurora. Her name made her even more lovely. Unfortunately, I had a hard time saying her name. This name and Rory make me think of 30 Rock and the 'Rural Juror...' Personally I think the name is beautiful, but the pronunciation is too awkward. I think that a Canadian named Aurora would have a much easier time with the spelling. We add U's into quite a few words and the majority of our population is quite familiar with the word in the context of "Aurora Borealis." Personal experiences with the name Aurora: | Edit I love my name Aurora (: I get so many comments on how beautiful it is. Recently I heard a young woman state this at a local store, "We changed her name to Aurora" When I was growing up in the Philippines, I hated my name because it sounded so old and I couldn't have a cute nickname. I ended up with "Pinky" or "Au-au". I remember giving my mother quite a hard time for naming me, Aurora. Also, Aurora is quite a common name in the Philippines.

It's the first name of the wife of President Manuel Quezon - so there's a town, province, major boulevard etc named after her. When I was in college, my foreign friends would ask if "Pinky" was my real name and when I replied, "No, it is actually Aurora", they recommended that I start using my real name. So when I left for the United States after graduation, I recalled their comments and began the new chapter in my life simply as "Aurora". As an adult woman, I love my name - I've grown into it I get compliments about my name at least once a week! However, I find few people can actually spell it properly - the "U" is often left out. I have also found the it is hard for people to spell my name correctly. I chose to name my first daughter Aurora when I was in the 5th grade. Main reason because of it's uniqueness, there aren't many with the name (in my opinion) in the USA. When I first heard the name Rory I thought it was so ugly and it sounded like roar to me. now it's my daughters nickname and I LOVE it. I have definitely eaten my words!

I think the name Aurora is absolutely beautiful and chose it for my daughter for that reason and because it has historically not been as popular in the US. The only source of irritation with the name for me is that I would prefer that it's recognized as the Goddess of the Dawn, but more often I get, "Oh, that's Sleeping Beauty!" I'd prefer my daughter stay as far from the Disney princesses as possible and like the mythology reference much better than the Disney one. We call our daughter Rory and it suits her perfectly! We chose to name our second daughter Aurora. It is a beautiful name and suits her to a t. I often would get the sleeping beauty comment but honestly must have been living under a rock as I had no idea this was her name till our Aurora came along. She gets called Rory or Ror most of the time. It is defiantly becoming more popular in Australia and people always comment to me what a pretty name it is. Nicknames for Aurora: | Edit Aura, Aury/Aurie, Ro, Rory/Rori, Rora, Au-au, Roar-Roar, Ratz, Arrie, Rors/Rorsie Meanings and history of the name Aurora : | Edit Roman goddess of the dawn.

The Greek goddess equivalent is Eos. "Aurora borealis" means northern lights, "aurora australis" the same phenomenon in the southern hemisphere. To "see the aurora" refers to seeing this typically winter-time display of breathtaking beauty in the night sky. The beauty of the aurora borealis has contributed to the popularity of this name in the state of Alaska, where the aurora can frequently be seen. Famous real-life people named Aurora: | Edit Aurora Cunha, Portuguese long-distance runner Aurora Karamzin, Finnish philanthropist Aurora "Rory" Block, American musician Elder daughter of Robyn Brown, from TLC's Sister Wives Aurora Perrineau, American actress and daughter of actor Harold Perrineau Aurora Aksnes, known mononymously as Aurora, Norwegian singer-songwriter Aurora in song, story & screen: | Edit Aurora De Martel is a main character in the CW's show " The Originals." Princess Aurora was the real name of Disney's Sleeping Beauty (she went incognita as "Briar Rose"). Aurora is a song by Italian singer Eros Ramazzotti.

Aurora Greenway, lead character in Terms of Endearment, played by Shirley MacLaine. Cities in Colorado and Illinois - the latter of which was the prominent setting for the SNL movie Wayne's World. Aurora is a song from The Foo Fighter's There Is Nothing Left to Lose album. Aurora Zogoiby is a character in Salman Rushdie's novel, The Moor's Last Sigh. Aurora Aceveda, a fictional character in the television series The Shield Aurora is the female lead in the 1993 Tony winner for Best Musical, Kiss of the Spider Woman. The show includes the song Her Name is Aurora. Aurora Teagarden is the main character in Charlaine Harris's book series, The Aurora Teagarden Mysteries. Aurora Borealis and the Aurora Australis About Watch and Favorite Watch Watching this resources will notify you when proposed changes or new versions are created so you can keep track of improvements that have been made. Favorite Favoriting this resource allows you to save it in the “My Resources” tab of your account. There, you can easily access this resource later when you’re ready to customize it or assign it to your students.

Aurora Borealis and the Aurora Australis Aurora borealis and australis are glowing sky phenomena that occur when charged particles from the sun excite atmospheric molecules. Learning Objective Recall how and why the aurora forms. Key Points An aurora is a natural light display in the sky, particularly in the high-latitude (arctic and antarctic) regions, that is caused by the collision of energetic charged particles with atoms in the high-altitude atmosphere . Auroras result from emissions of photons in the Earth's upper atmosphere (above 80 km), from ionized nitrogen atoms regaining an electron , and from electrons from oxygen and nitrogen atoms returning from an excited state to ground state . The solar wind coming from the sun is the origin of the charged protons and electrons that excite oxygen and nitrogen and cause auroras. The aurora's color depends on the type of atom that is excited and how its electrons return from those excited states to the ground state.

Terms Full Text Auroras An aurora (plural aurorae or auroras; from the Latin word aurora forsunrise) is a natural light display in the sky, particularly in the high-latitude (arctic and antarctic) regions; it is caused by the collision of atmospheric atoms with energetic, charged particles coming from space. The charged particles originate in the magnetosphere and solar wind and then are directed by the Earth's magnetic field into the atmosphere. The Earth's magnetic field directs the charged particles to the Earth's magnetic poles—as a result, it is the easiest to see the aurora near the poles. An aurora is classified as either a diffuse or a discrete aurora. A diffuse aurora is a featureless glow in the sky that may not be visible to the naked eye even on a dark night and defines the extent of the auroral zone (the area in which auroras are visible). Discrete auroras are sharply-defined features within the diffuse aurora; they vary in brightness from barely visible to bright enough for reading a newspaper at night.

In northern latitudes, the effect is known as the aurora borealis (or the northern lights), named by Pierre Gassendi in 1621 after the Roman goddess of dawn, Aurora, and the Greek name for the north wind, Boreas. The northern lights have had a number of names throughout history: the Cree called the phenomenon the "Dance of the Spirits"; in Europe in the Middle Ages, the auroras were commonly believed to be a sign from God. Auroras seen near the magnetic pole may be high overhead, but from farther away, they illuminate the northern horizon as a greenish glow or sometimes a faint red, as if the sun were rising from an unusual direction. Discrete auroras often display magnetic field lines or curtain-like structures. They can change within seconds or glow unchanging for hours, most often in fluorescent green. The aurora borealis most often occurs near the winter equinox when it is dark for long periods of time. Clouds in the sky and any light (natural sunlight or man-made light) can prevent the possibility of seeing the aurora from the ground. The aurora borealis' southern counterpart, the aurora australis (or the southern lights), has almost identical features.

It changes simultaneously with the northern auroral zone and is visible from high southern latitudes in Antarctica, South America, New Zealand, and Australia. Some images of aurora borealis. What Causes the Aurora? Auroras result from emissions of photons in the Earth's upper atmosphere (above 80 km, or 50 mi), from ionized nitrogen atoms regaining an electron, and from oxygen and nitrogen atoms returning from an excited state to ground state. They are ionized or excited by the collision of solar wind and magnetospheric particles (such as high energy protons and electrons) funneling down and accelerating along the Earth's magnetic field lines. The excited particles' energy is lost by the emitting photon or colliding with another atom or molecule . The solar wind consists of free, high-energy electrons and protons that originate at the sun. In the vacuum of space, they maintain their energy because the normal method of energy loss, collision, is not possible due to the low particle density . Instead, this energetic flow of particles is attracted to the Earth's magnetic field, where it collides with oxygen and nitrogen in the top regions of the atmosphere.

The movement of these charged particles also causes electricity, which serves to further excite the molecules in the Earth's atmosphere. This energy serves to move the electrons in nitrogen and oxygen from their ground state up to an excited state, where they can then decay back to the ground state by emitting photons of visible light (see the concept on emission spectra for more information). Collisions with other atoms or molecules can absorb the excitation energy and prevent emission. Oxygen emissions are green or brownish-red, depending on the amount of energy absorbed. Nitrogen emissions are blue if the atom regains an electron after it has been ionized and red if the atom returns to ground state from an excited state. Oxygen is unusual in terms of its return to ground state: it can take three-quarters of a second to emit green light and up to two minutes to emit red. Because the very top of the atmosphere has a higher percentage of oxygen and is sparsely distributed, collisions preventing emission are rare enough to allow oxygen the time needed to emit red light. Collisions become more frequent farther down in the atmosphere, and red emissions do not have time to happen; eventually, even green light emissions are prevented.

This is why there is a color differential with altitude: at high altitudes, oxygen's red emissions remain; then, oxygen's green emissions and nitrogen's blue and red emissions; and finally, only nitrogen's blue and red emissions are left, because collisions prevent oxygen from emitting any light at all. Green is the most common color of all auroras, followed by pink, a mixture of light green and red, pure red, yellow (a mixture of red and green), and pure blue. Aurora Village Aurora Village Aurora Information What is the Aurora Borealis? The aurora is the effect that is caused when charged particles in solar winds are pulled into the atmosphere by the earth’s magnetic force. This force is also what channels them towards our geomagnetic poles. When these particles collide with the gas atoms and molecules of earth’s atmosphere, the lights of the aurora are emitted. The more collisions there are, the brighter the lights are. The different colours of the aurora are created by the particles colliding with the different gasses in our atmosphere and because earth has two magnetic poles, we get the aurora borealis at the North Pole and the aurora australis at the South Pole.

Common Names For The Aurora The Aurora Borealis means “northern dawn” in Latin. In ancient Roman times, Aurora was the goddess of dawn while Borealis means northerly, hence the term aurora borealis. Most commonly, after aurora borealis, it is called the northern lights. Other variations of this include polar lights, northern polar lights, aurora polaris, and polar spirits. Where Is The Best Place To See The Northern Lights? We would have to say Yellowknife in the Northwest Territories of Canada, hands down. The city and surrounding area is situated directly beneath the aurora oval, which is a halo-like ring that is found around both magnetic poles of the earth. Although there are other places also just below the aurora oval, the Yellowknife area is deemed the best because of its relatively flat topography, coupled with few geographical obstructions. This allows for a higher percentage of clear weather, particularly in the winter, and therefore, a much higher viewing probability. When you stay with us for 3 nights of aurora-viewing, you have a 95 percent chance of seeing the aurora at least once.

Take a look at our Nightly Aurora Photo Log to see how often we have an aurora display at Aurora Village. Aurora Information Get in touch with us today. If you have any questions or need more information please call us. CALL +1 867-669-0006 What are the northern lights?(Everyday Mysteries: Fun Science Facts from the Library of Congress) What are the northern lights? The northern lights, one of several astronomical phenomena called polar lights (aurora polaris), are shafts or curtains of colored light visible on occasion in the night sky. Polar lights (aurora polaris) are a natural phenomenon found in both the northern and southern hemispheres that can be truly awe inspiring. Northern lights are also called by their scientific name, aurora borealis, and southern lights are called aurora australis. Sten Odenwald, author of The 23rd cycle, learning to live with a stormy star (New York, Columbia University Press, c2001), provides insight to how northern lights are formed: The origin of the aurora begins on the surface of the sun when solar activity ejects a cloud of gas.

Scientists call this a coronal mass ejection (CME). If one of these reaches earth, taking about 2 to 3 days, it collides with the Earth’s magnetic field. This field is invisible, and if you could see its shape, it would make Earth look like a comet with a long magnetic ‘tail’ stretching a million miles behind Earth in the opposite direction of the sun. When a coronal mass ejection collides with the magnetic field, it causes complex changes to happen to the magnetic tail region. These changes generate currents of charged particles, which then flow along lines of magnetic force into the Polar Regions. These particles are boosted in energy in Earth’s upper atmosphere, and when they collide with oxygen and nitrogen atoms, they produce dazzling auroral light. Odenwald further tells us "Aurora are beautiful, but the invisible flows of particles and magnetism that go on at the same time can damage our electrical power grid and satellites operating in space. This is why scientists are so keen to understand the physics of aurora and solar storms, so we can predict when our technologies may be affected." Can I see them anywhere? Yes.

Although more frequent at higher latitudes, closer to the poles (such as in Canada, Alaska, Antarctica), they have been seen closer to the equator as far south as Mexico. To view them, look in the direction of the closest pole (the northern horizon in the northern hemisphere, the southern horizon in the southern hemisphere). Can I see them at any time of the year? Yes. In some areas, such as Alaska or Greenland, they may be visible most nights of the year. And they occur at any time of the day, but we can’t see them with the naked eye unless it’s dark. What causes the colors and patterns? Colors and patterns are from the types of ions or atoms being energized as they collide with the atmosphere and are affected by lines of magnetic force. Displays may take many forms, including rippling curtains, pulsating globs, traveling pulses, or steady glows. Altitude affects the colors. Blue violet/reds occur below 60 miles (100 km), with bright green strongest between 60-150 miles (100-240 km). Above 150 miles (240 km) ruby reds appear.

Fun Facts about northern lights: According to Neil Bone (The aurora: sun-earth interactions, 1996), the term aurora borealis--northern dawn--is jointly credited to have first been used by Pierre Gassendi (1592-1655) and Galileo Galilei (1564-1642), who both witnessed a light display on Sept. 12, 1621. However, Bone also includes a description of the northern lights made 1,000 years prior by Gregory of Tours (538-594.) It included the phrase, "... so bright that you might have thought that day was about to dawn." Auroras have been observed since ancient times. The height of the displays can occur up to 1000 km (620 miles), although most are between 80-120 km. Auroras tend to be more frequent and spectacular during high solar sunspot activity, which cycles over approximately eleven years. Some displays are particularly spectacular and widespread and have been highlighted in news accounts.

Examples include auroral storms of August-September, 1859, Feb 11, 1958, (lights 1250 miles wide circled the Arctic from Oregon to New Hampshire) and March 13, 1989, (the whole sky turned a vivid red and the aurora was seen in Europe and North America as far south as Cuba). Legends abound in northern cultures to explain the northern lights. Some North American Inuit call the aurora aqsarniit (“football players”) and say the spirits of the dead are playing football with the head of a walrus. Often legends warn children that the lights might come down and snatch them away. June 1896, Norwegian Kristian Birkeland, the “father of modern auroral science,” suggested the theory that electrons from sunspots triggered auroras. Yellowknife (Northwest Territories, Canada) is the capital for aurora tourism. The earliest known account of northern lights appears to be from a Babylonian clay tablet from observations made by the official astronomers of King Nebuchadnezzar II, 568/567 BC.

Some people claim to hear noises associated with the northern lights, but documenting this phenomenon has been difficult. Related Web Sites Aurora borealis by Pål Brekke - This is an article on the aurora borealis by Pål Brekke published in Scandinavian Review, Fall 2008, v. 93. Auroras: Paintings in the Sky - Lots of links, pictures, includes specific information for teachers. Cosmicopia: an abundance of cosmic rays - Information on Space Weather from NASA, including an animation of a coronal mass ejection's impact on the Earth's magnetosphere. NOAA POES Auroral Activity - Technical information and data collected from POES (Polar-orbiting Operational Environmental Satellite) on its most recent polar pass. May help predict where to see auroras. Solar Storms - This site presents information about the human impacts of solar storms and space weather. Space Weather Research Explorer: Auroras - With data from POES, this Exploratorium site packages the information in a simpler format. Further Reading Aurora Borealis, Alaska Kids' Corner, State of Alaska From "The Ballad of the Northern Lights" by Robert Service by Dr.

Neil Davis (reprint) The Aurora, also known as the Northern Lights, has mystified people down through the ages, scientists, poets, and lay persons alike. Written records of so-called "great auroral displays" date back more than two thousand years. Sometimes the Aurora over Alaska and other auroral zones is barely visible or appears colorless and unmoving. But at other times the auroras can be incredibly bright, multihued and fast moving. Tall green curtains of lights, red tipped at their bottoms, stretch from horizon to horizon. They ripple and sway, fold and unfold, then suddenly disappear, only to reform in a new shape minutes later. For those who live in Alaska, the Aurora is a part of northern life. Fall, winter and spring is the special season for viewing the great lights for residents and off-season visitors. Some Alaskans have "Aurora Alerts;" when a display begins, the first person to spot them begins a phone tree to get the word out. The "pulsating Aurora" is one form of Northern Light common during the post-midnight hours. It blinks on and off every few seconds as though controlled by some mysterious unseen hand in the sky flicking a switch.

The great auroral displays are spectacular global events during which the Aurora spreads down from the polar regions to cover as much as two thirds of the earth's skies with bright, fast-moving masses of light, often deep red in color. The rare "great auroral displays" follow one or two days of violent solar flares in the vicinity of major sunspots. These solar flares cast out vast streams of electrically charged particles which stream down into the earth's atmosphere. These particles, mostly electrons and protons, are steered away from the tropical regions by the earth's magnetic field. Striking the gases of the earth's high atmosphere, the charged particles glow. It is exactly the same thing that happens in a television tube: complex streams of electrons within the TV strike the phosphor coated face of the tube, and cause it to glow, creating the colored moving patterns we see from our living room couches. Outside, at night, we can look up at that great star-studded television tube in the sky; if the Aurora is out and no clouds are about, the colored patterns will be there too. Even though "great auroral displays" appear infrequently, spectacular displays of Aurora are common in Alaska and other auroral zone locations.

This is because the sun is always sending out a stream of electrons and protons. They make up the solar wind which blows constantly toward the earth and other planets. Enough of the solar wind particles come into the earth's high atmosphere at the auroral zone to create continuous Aurora, summer, winter, fall and spring. Although much is known about the Aurora, this fascinating phenomenon still withholds some of its mysteries. For example, scientists do not yet understand why the Aurora is so highly structured. For the University of Alaska Fairbanks, this continues to be an important area of study. The most beautiful Aurora is composed of thin sheets that stretch upward a hundred miles or more and extend across the sky from horizon to horizon, like gigantic ribbons set on edge high above and parallel to the earth's surface. These arcs and bands whip and weave across the sky, and bright rays ripple along them at fantastic speed. Some of these intricate multicolored forms have a thickness of only 100 meters, about the length of a football field, yet may be several hundred kilometers tall and well over 1,000 kilometers in length.

It boggles the mind to realizeas has been proven by simultaneous observation in the two hemispheresthat these sharply defined auroral forms have an identical or nearly identical mate in the southern hemisphere, out of sight and almost a world away. Joined together by an invisible magnetic bond that arches far above the Equator, each pair of mated auroral dancers move across the cold polar skies in perfect harmony. Each motion or brightness change in one hemisphere is mirrored in the other, on a time scale of less than a fraction of a second. A most curious and highly controversial question involves auroral sound. Although I've never heard one, my wife has and so have several scientists I know. Some reports of hearing noises associated with auroral displays may be erroneous impressions, but I am convinced many others are not. Hundreds of written reports indicate noises are sensed when a particular type of fast-Aurora is nearly overhead. Some people sense whistling and crackling noises, even when they close their eyes. The reports of auroral sound make it certain that the unknown cause of the apparent sound is in the vicinity of the hearer, not in the Aurora itself.

Most likely, the reported noises are related to electrical phenomena which accompany certain types of bright Aurora. No matter how many auroras one may have seen, a good high-latitude display, as seen in Alaska, sends tingles up the viewer's spine. Even a moderate display seen at the auroral zone in the 49th state can be far more exciting to watch than one of the rare "great displays." The best of words and photographs fail to capture the magnificence of the high-latitude Aurora, although some of Robert Service's poetry may come close. THE AURORA has a curtain-like shape, and the altitude of its lower edge is sixty or seventy miles, about ten times higher than a jet aircraft flies. AURORAS OCCUR along ring-shaped regions around the north and south geomagnetic poles. Fairbanks, Alaska, is a good place for Aurora watching because it is under this region in the north, where people see Aurora Borealis, or northern lights; the southern Aurora is Aurora Australis. LIKE A NEON SIGN, auroral light is produced by a high-vacuum electrical discharge. It is powered by interactions between the sun and earth. The light is a glow from atoms and molecules in the earth's upper atmosphere.

THE SUN IS a ball of gases that is so hot its outermost part blows away as the solar wind. Consisting of charged particles, this tenuous gas travels to earth in about three days. Because the earth's magnetic field prevents the solar wind from penetrating our atmosphere, its solar particles stream around our planet, encasing earth and its magnetic field within a comet-shaped cavity called the magnetosphere. THE SOLAR WIND powers the gigantic electrical discharge process, causing the magnetosphere to behave as a generator that produces up to ten million megawatts of electrical power. THE UPPER ATMOSPHERE contains, at the lower edge of the Aurora, a thin and partly ionized layer called the ionosphere. Reflected by the ionosphere, radio waves can propagate great distances by bouncing between it and the ground. AURORAL DISPLAYS INDICATE that the ionosphere and our protective atmosphere are being energized by the electric power generated in the magnetosphere. As these electrical currents are discharged in the ionosphere many phenomena are produced, including the visible emissions we recognize as the Aurora and magnetic storms. AURORAS ARE SIMILAR to color television images.

In the picture tube, a beam of electrons controlled by electric and magnetic fields strike the screen, making it glow in colors that vary with the screen's phosphor. Auroral color depends on the type of atoms and molecules struck by the energetic particles, particularly electrons, that rain down along earth's magnetic field lines in the discharge process. Each atmospheric gas glows with a specific color, depending on whether it is ionized or neutral, and on the energy of the particle hitting the atoms and air molecules. THE BRIGHTEST and most common auroral color, a brilliant yellow green is produced by oxygen atoms at roughly 60 miles altitude. High-altitude oxygen atoms (about 200 miles) produce rare, all-red auroras. Ionized nitrogen molecules produce blue light, neutral nitrogen molecules create purplish-red lower borders and ripple edges. AURORAL INTENSITY varies from night to night and during a single night, with best viewing usually from late evening through the early morning hours. Strong auroras can be seen in the continental U.S., particularly in the north during sunspot maximum years.

The number of sunspots (a sign of solar activity) varies according to an eleven-year cycle a few years after a maximum sunspot year (such as 1991), auroras in high-latitude are more numerous. There's also a slight tendency for more auroras in spring and fall. THE MAGNETOSPHERE protects us from direct effects of the solar wind, but auroras can seriously disrupt radio communications, radio navigation, some defense-related radar systems, and power transmission lines. Current created by changing magnetic fields accompanying Aurora cause corrosion in pipes, including the trans-Alaska pipeline. Come to Interior or Northern Alaska during the late fall or winter months, particularly March when the skies are often clear and dark. Plan to spend a few days because the Aurora is, like the weather, variable. Aurora-watching and auroral photography is best done on clear, moonless nights. When flying between Seattle and Anchorage or Fairbanks in wintertime, take a night flight and sit on the right-hand side of the airplane going north (left-hand side of the airplane going south). Don't be misled by seeing Aurora below the aircraft's wing; that Aurora is high over western Canada, at least 50 miles above the ground.

The places where the auroral forms appear to "touch" the ground are about 600 miles distant. To be sure of seeing Aurora, plan to stay up most of the night. The best hours often are near midnight. Wear warm clothing. Stay away from city or other bright lights that can obscure the views. For a real treat, go to a hot springs resort where you can lay in an outdoor hot pool and watch the Aurora in comfort. If you plan to photograph the Aurora, bring a tripod. Bright as it is, the Aurora still requires time exposures of several seconds. Summer visitors to Fairbanks can view and purchase a video tape showing actual auroral motions at the University Museum. Each evening at nearby Ester, Alaska, Photosymphony Productions puts on a unique musical and photographic show entitled "The Crown Of Light" containing some of the finest photographic images of Aurora available anywhere.

Links for More Information: Aurora Borealis: What Causes the Northern Lights & Where to See Them Aurora Borealis: What Causes the Northern Lights & Where to See Them By SPACE.com Staff | February 10, 2015 08:15pm ET MORE Skywatcher Shawn Malone took this photo of the aurora March 15-16, 2012. She writes: "[A]urora activity picking up casts a bright reflection off of Lake Superior, Marquette, MI." Credit: Shawn Malone The northern lights, or aurora borealis, offer an entrancing, dramatic, magical display that fascinates all who see it — but just what causes this dazzling natural phenomenon? At the center of our solar system lies the sun, the yellow star that sustains life on our planet. The sun's many magnetic fields distort and twist as our parent star rotates on its axis. When these fields become knotted together, they burst and create so-called sunspots . Usually, these sunspots occur in pairs; the largest can be several times the size of Earth's diameter.

This image from NASA's Solar Dynamics Observatory shows the sun as it appeared in extreme ultraviolet wavelengths on March 5, 2012 just after a major solar flare. Credit: NASA/SDO/AIA At the center of the sun, the temperature is 27 million degrees Fahrenheit (15 million degrees Celsius). As the temperature on its surface rises and falls, the sun boils and bubbles. Particles escape from the star from the sunspot regions on the surface, hurtling particles of plasma, known as solar wind, into space. It takes these winds around 40 hours to reach Earth. When they do, they can cause the dramatic displays known as the aurora borealis. [Infographics: How the Northern Lights Work & Anatomy of Sun Storms & Solar Flares ] Sunspots and cycles The sunspots and solar storms that cause the most magnificent displays of the northern lights occur roughly every 11 years. The solar cycle peaked in 2013, but it was the weakest solar maximum in a century. [ Photos: Amazing Auroras of 2014 ] "This solar cycle continues to rank among the weakest on record," Ron Turner of Analytic Services, Inc.

who serves as a Senior Science Advisor to NASA's Innovative Advanced Concepts program, said in a statement. Since record-keeping of the ebb and flow of the sun's activity began in 1749, there have been 22 full cycles. Researchers monitor space weather events because they have the potential to affect spacecraft in orbit, knock out power grids and communications infrastructure on Earth, and amp up normal displays of the northern and southern lights. Scientists are also investigating how fluctuations in the sun's activity affect weather on our planet. Particles and polar attraction Earth is constantly bombarded with debris, radiation and other magnetic waves from space that could threaten the future of life as we know it. Most of the time, the planet's own magnetic field does an excellent job of deflecting these potentially harmful rays and particles, including those from the sun. Particles discharged from the sun travel 93 million miles (around 150 million km) toward Earth before they are drawn irresistibly toward the magnetic north and south poles. As the particles pass through the Earth's magnetic shield , they mingle with atoms and molecules of oxygen, nitrogen and other elements that result in the dazzling display of lights in the sky.

An Expedition 30 crew member took this photo of the North Atlantic with an aurora on March 28, 2012. Credit: NASA The auroras in Earth's Northern Hemisphere are called the aurora borealis. Their southern counterpart, which light up the Antarctic skies in the Southern Hemisphere, are known as the aurora australis . What causes the colors? The colors most often associated with the aurora borealis are pink, green, yellow, blue, violet, and occasionally orange and white. Typically, when the particles collide with oxygen, yellow and green are produced. Interactions with nitrogen produce red, violet, and occasionally blue colors. The type of collision also makes a difference to the colors that appear in the sky: atomic nitrogen causes blue displays, while molecular nitrogen results in purple. The colors are also affected by altitude. The green lights typically in areas appear up to 150 miles (241 km) high, red above 150 miles; blue usually appears at up to 60 miles (96.5 km); and purple and violet above 60 miles.

These lights may manifest as a static band of light, or, when the solar flares are particularly strong, as a dancing curtain of ever-changing color. History of the auroral lights For millennia, the lights have been the source of speculation, superstition and awe. Cave paintings in France thought to date back 30,000 years have illustrations of the natural phenomenon. In more superstitious times, the northern lights were thought to be a harbinger of war or destruction, before people really understood what causes them. Many classic philosophers, authors and astronomers, including Aristotle, Descartes, Goethe and Halley, refer to the northern lights in their work. As early as 1616, the astronomer Galileo Galilei used the name aurora borealis to describe them, taking the name of the mythical Roman goddess of the dawn, Aurora, and the Greek name for wind of the north, Boreas. The aurora australis, or the southern lights, occur around the south polar region. But, since the South Pole is even more inhospitable than the North Pole, it is often trickier to view the southern lights.

Astrophotographer Antti Pietikäinen took this aurora photo on Jan. 24, 2012 in Muonio, Lapland, Finland. Credit: Antti Pietikainen Where to see the lights The best places to see the northern lights are Alaska and northern Canada, but visiting these vast, open expanses is not always easy. Norway, Sweden and Finland also offer excellent vantage points. During periods of particularly active solar flares, the lights can be seen as far south as the top of Scotland and even northern England. [ A Guide for Watching Earth's Auroras ] On rare occasions, the lights are seen farther south. They were first observed by European settlers in New England in 1791. In "Historical Storms of New England," published in 1891, Sidney Perley wrote, "May 15, 1719, the more beautiful and brilliant aurora borealis was first observed here as far as any record or tradition of that period inform us, and it is said that in England it was first noticed only three years before this date.

In December of the same year the aurora again appeared, and the people became greatly alarmed, not dreading it so much as a means of destruction but as precursor of the fires of the last great day and a sign of coming dangers." When to see the lights The northern lights are always present, but winter is usually the best time to see them, due to lower levels of light pollution and the clear, crisp air. September, October, March and April are some of the best months to view the aurora borealis. The lights are known to be brighter and more active for up to two days after sunspot activity is at its highest. Several agencies, such as NASA and the National Oceanic and Atmospheric Administration , also monitor solar activity and issue aurora alerts when they are expected to put on a particularly impressive show. Additional reporting by Nola Taylor Redd, Space.com Contributor Additional resources What is the Aurora Borealis? - Universe Today Universe Today What is the Aurora Borealis? Article Updated: 25 Sep , 2016 by Jean Tate [/caption] The aurora (plural aurorae) borealis has many other names: northern lights, northern polar lights, polar lights, and more.

An aurora borealis is light seen in the sky, nearly always at night, in the northern hemisphere, commonly green but also red and (rarely) other colors; often in the shape of curtains, sheets, or a diffuse glow (when seen from the ground). Northern lights are most often seen at high latitudes – Alaska, Canada, northern Scandinavia, Greenland, Siberia, and Iceland – and during maxima in the solar cycle. Aurora australis – southern lights – is the corresponding southern hemisphere phenomenon. Seeing a bright auroral display may be on your list of ‘things to see before I die’! Yep, they are nature’s light show par excellence. Aurora borealis occur in the Earth’s ionosphere, and result from collisions between energetic electrons (sometimes also protons, and even heavier charged particles) and atoms and molecules in the upper atmosphere. The ultimate origin of the energy which powers the aurora borealis is the Sun – via the solar wind – and the Earth’s magnetic field.

Interactions between the solar wind (which carries its own tangled magnetic fields) and the Earth’s magnetic field may cause electrons (and other particles) to be trapped and accelerated; those particles which do not escape ‘downstream’ to the magnetic tail ‘touch down’ in the atmosphere, close to the north magnetic pole. The different colors come from different atoms or ions; green and red from atomic oxygen, nitrogen ions and molecules make some pinkish-reds and blue-violet; purple is the appearance of combined colors from nitrogen ions and helium; neon produces the very rare orange. The ionosphere is home to most aurorae borealis, with 100-300 km being typical (this is where green is usually seen, with red at the top); however, some particularly energetic particles penetrate much deeper into the atmosphere, down to perhaps 80 km or lower (purple often comes from here). Viewed from space, when the northern lights are intense they appear as a ring (an oval actually), the auroral zone, with the north magnetic pole near the center. The University of Alaska Fairbanks’ Geophysical Institute has a good FAQ on the aurora borealis.

Magnetic fields plus solar wind … so you’d expect aurorae on Jupiter and Saturn, right? And auroral displays around the magnetic poles of these planets are now well documented. Aurorae have also been imaged on Venus, Mars, Uranus, Neptune, and even Io.

Question: What is a more common name for the Aurora Borealis?
Answer: The Northern Lights