Cartes Pour Fêtes Annuelles Joyeux Noё l - Aurora Borealis

A multi-colored, fractal rendering of the aurora borealis, ou Northern Lights, superimposed on a digital painting of snow-covered mountains. "Joyeux Noё l" appears en rouge. The aurora borealis (ou Northern Lights), named after the roman goddess of dawn, Aurora, and the Greek name for the north wind, Boreas. Many cultural groups have legends about the lights. Dans medieval times, the occurrences of auroral displays verses as harbingers of war or famine. The Maori of New Zealand shared a en blâmer many northern people of Europe and North America that the lights were reflections from torches or campfires. The Menominee Indians of Wisconsin arbitraire ved that the lights indicated the location of manabai'wok (giants) who e the spirits of great hunters and fishermen. The Inuit of Alaska arbitraire that the lights were the spirits of the animals they hunted: the seals, salmon, deer and beluga whales. Other aboriginal peoples arbitraire ved that the lights were the spirits of their people. The Connection between the Northern Lights and sunspot activity suspected as far back as 1880. Thanks to research Conducted since the 1950, we now know that electrons and protons from the sun are blown towards the earth on the solar wind. Note : 1957-58, International Geophysical Year and the atmosphere was studied extensively with balloons, radar, rockets and Satellites. Rocket research is silencieux conducted by scientists at Poker Flats, a facility under the direction of the University of Alaska at Fairbanks. Le tempérament de la sun's atmosphere is millions of degrees. At this temperature, collisions between gas molecules frequent and explosif. 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. 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 in the higher layers (thermosphere). These collisions emit light that we perceive as the dancing lights of the north (and the south). Most aurorae occur in a band known as the auroral zone, which is typically 3° to 6° dans latitudinal extent and at all local times or longitudes. The auroral zone is typically 10° to 20° from the magnetic pole defined by the axis of the Earth's magnetic dipole. During a geomagnetic storm, the auroral zone veut expand to lower latitudes. The diffuse aurora is a featureless glow in the sky which may not visible to the unaided eye on a dark night and defines the extent of the auroral zone. The discrete aurora are sharply defined feobjets within the diffuse aurora which vary in brightness from just barely visible to the unaided eye to bright enough to read a newspaper at night. Discrete aurorae are usually observed only in the night sky because they are as bright as the sunlit sky. Aurorae occasionally occur poleward of the auroral zone as diffuse patches or arcs (polar cap arcs, which are generally invally invisible to the unaided eye. Because the phenomena occurs near the magnetic poles, northern lights have been 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 (en Amérique du Nord) are in the northwestern parts of Canada, particularly the Yukon, Nunavut, Northwest Territories and Alaska. Auroral displays can be lacs 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 ofen as they are concentrated in a ring around Antarctica and the southern Indian Ocean. Les Auroros appear dans les Many Colors. Variations in color 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. Nitrogène produces blue or purplish-red aurora. 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 . Structures de rideau de fer pour les zones magnétiques de la Terre. The auroras that resulted from the great geomagnetic storm on both 28 août et 2 septembre 1859 are thought the most spectacular in recent recorded history . C'est ce que reported by the New York Times a écrit à Boston on Friday 2 septembre 1859 the aurora, un truc "si brillant that at about one o'clock ordinary print could be read by the light". The aurora is thought to have produced by one of the most intense coronal mesure ejections in history, very near the maximum intensity that the Sun is thought to be peut of producing. Donc, il est apparu que c'est la raison pour laquelle le premier temps de la vie de la phénomena of auroral activity and electricity est une chose qu'il n'y a pas d'ambiguïously linked. This insight ce qui est made possible not only due to scientific magnétomètre measurements of the era, but as a result of a significant portion of the 125 000 miles (201 000 km) of telegraph lines then in service being significatifs disrupted for many hothroughout the storm. Some telegraph lines, however, seem to have been of the appropriate length and orientation to produce a sufficient geomagnetically induced current from the electromagnetic field to allow for continued communication with the telegraph operator power switched off. Both Jupiter and Saturn have magnetic fields much stronger than Earth's (Jupiter's equatorial field strength is 4.3 gauss, compared to 0.3 gauss for Earth), et both have large radiation belts. Auroras have been observed on both, most clearly with the Hubble Space Telescope Uranus and Neptune have donc observed to have auroras.