Auroras usually occur in ring-shaped areas centered around the magnetic poles of earth. The complete rings, called auroral ovals, can only be seen from space.The best place to see the aurora are in Alaska, Canada and Scandinavia, during late evening hours.
Aurora are classified as diffuse and discrete. The diffuse aurora is a fuatureless glow in the sky that may not be visible to the naked eye, even on a dark night. The discrete aurora are sharply defined features within the diffuse aurora that vary in brightness from just barely visible to the naked eye to bright enough to read a newspaper by at night. Discrete aurora are usually seen only the night sky, because they are not as bright as the sunlit sky.
The color of aurora depends on which gas is being excited by the electron s and on how much energy is being exchanged. Oxygen emits either a greenish yellow light ( the most familiar colour in aurora) or a light light, nitrogen generally gives of a blue lights. The oxygen and nitrogen molecules also emit ultraviolet light, which can only be detected by special cameras on satellites.
The shapes of aurora depends on where in the magnetosphere the
electron came from and on what caused them to precipitate into the atmosphere.
Dramatically different aurora shapes can be seen in a single night.
Folktales and travelers tales say that the aurora can generate noise such as claps, crackles and static sounds, usually faint and brief. For a long time scientists were dubios, since sound has been hard to document, and auroral display themselves are too high in the sky for them to be heard on the ground.
Folktales and travelers tales say that the aurora can generate noise such as claps, crackles and static sounds, usually faint and brief. For a long time scientists were dubios, since sound has been hard to document, and auroral display themselves are too high in the sky for them to be heard on the ground.
Sumber : google/aurora-fenomena
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