Excel is A purple strip, the arc-shaped in the sky, sometimes surrounded by green splashes of color: Amateur photos of this "Steve" referred to light appearance bring atmosphere researchers for three years to Ponder.
Because so many of Steve's weird. Typically, the polar lights are blue or green. They occur when electrically charged particles of the solar winds are deflected by the magnetic field of the earth towards the poles, where they collide in the atmosphere with oxygen - or nitrogen atoms and light effects. But Steve shines purple pink to light, and is also significantly further South than typical Auroras. Sometimes the purple bow is also accompanied by a green Flickering, the scientists "picket fence" have been baptized.
light-emitting phenomenon "Steve" with a "picket fence"(photo by Rocky Raybell)
researchers from the Boston University reports now of a possible cause for the phenomenon, or rather phenomena, because, as the Team Yukitoshi Nishimura in the journal Geophysical Research Letters writes, go back to the pink bow and the green picket fence on different phenomena.
friction in the upper atmosphere
The reddish strip is formed, therefore, by a kind of frictional heat in the higher areas of the earth's atmosphere. "An Aurora is characterized by a precipitation of particles, electrons and protons, which fall into our atmosphere," explains Bea Gallardo-Lacourt, author of the study. "The atmospheric lights by Steve stems from a heating without particle precipitation." The researchers compare it with a conventional bulb in which a tungsten wire is heated until it glows. Where does the energy for this friction comes in the atmosphere, can not explain the researchers, but to finally.
For the study, they used, among other things, satellites, the register permanently the magnetic field of the earth measured to the influx of particles from space. Their data compared with Amateur footage of Steve. The atmosphere could exclude researchers that Steve is high-energy protons. Instead, they came at the time of a luminescence in a particularly intense and fast Form of the solar winds in the 25 000-km altitude. This "intensive waves" seem to be for the friction heat in the atmosphere.
on the other hand is the green slatted back fence according to the satellite data on electrons to flow from space to earth, so the polar lights similar. He will be speaking much more to the South, make it unique, Gallardo-Lacourt. In addition, half of the ball difficult one of the picket fence at the same time on the Northern as on the southern hemisphere.