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Why are the northern and southern lights different?



Dazzling green and red light regularly dance through the night sky above the northern and southern poles of the Earth. For decades, scientists have predicted that when both polar lights shine in both regions, blinking patterns reflect each other. But in 2009 they found that it was not. They were surprised, and unexpectedly why. Now a group of researchers from Norway, Germany, and the United States found the culprit: the roaring sun

Earth generates a magnetic field that looks like a magnetic strip passes from the South Pole through its core to the North Pole. Field lines bend outside from both poles, far beyond the atmosphere, and the outer arcs form the boundary of the magnetic bubble around our planet. This magnetosphere is repelled from charged particles moving toward us from outer space. Polar glow arise when charged particles emitted by the sun break through the magnetosphere. Particles are accelerated along the lines of the magnetic field of the Earth to the icy polar regions. When they fall into the atmosphere, they collide with atoms and molecules, producing colorful photons that illuminate the sky

When the force lines around the Earth are symmetrically curved magnetic fields, the polar glow must appear in identical locations in the northern and southern hemispheres . And, if you could watch both light displays at the same time, they would look almost the same. But this scenario is actually "fairly rare," says Aaron Ridley, a magnetosphere researcher at the University of Michigan who was not involved in a new study.

This is because the sun also has a powerful magnetic field. It changes the path that traces through the Earth's lines, rubbing the lines at the bottom of our planet, directed toward the sun, and extending the lines on the night side, creating a magnetic tail. As a result, the magnetic field of the Earth traces the contour of the house ̵

1; the rounded head of the insect, directed toward the sun, and its elongated body and tail point away

. The earth But most of the time, the sun and the poles of the earth are skewed, creating the shape of a household with a curve tail for the latter case. The fluctuating sunshine "spins" the tail, breaking and reforming its field lines – events called restoration. Scientists believed that the restoration of the senses displaced one polar radiance relative to another. But Nikolai Ostgaard, a space scientist from the University of Bergen in Norway, and his colleagues examined this idea and found that it was wrong. They discovered another effect that is responsible for auroral differences: the solar magnetic field compresses the magnetic field of the Earth unevenly. They also showed an explosion, or "subboree", of additional charged particles in the tail, which could undo the effects of uneven compression, eliminate inconsistencies.

The team studied images captured by a spacecraft for 10 pairs of polar shadows that occurred simultaneously in the northern and southern hemispheres between 2001 and 2005. Polar glow began in asymmetric places on the globe. For example, on November 15, 2002, southern lights (aurora australis) broke out west of the northern shade (aurora borealis). But when the light display continued, their positions were displaced, becoming more symmetrical. The changes coincided with the subburium

According to these observations to the activity of the magnetostyle of the Earth, Østgaard and colleagues found that the events of re-engagement coincided with the decrease of the astronomical asymmetries. "Repeated connection has the opposite effect, as people thought," says Ostgard. Instead, as it continues, it is important how the magnetic field of the Sun compresses the Earth. Modeling and observation of his team show uneven compression of the northern and southern hemispheres, tilting the field lines of the Earth and moving the polar light. Violation of the lines of the field – which they observe, occurs when the substrates have fallen – releases the magnetic pressure accumulated from compression and removes the oblique. Observation "surprising", considering the disagreement with the previous models. That the team can understand the physics behind the polar shine, looking at the picture is "very cool," adds Ridley. They can also interfere with the positioning of GPS, as well as electrical networks and other technological systems. Scientists can not accurately predict where and when the space weather will fall, says Muller-Vodardz. But at least they solved one shining secret in the night sky.


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