Sandra Martindale, age 12, of Sand Springs, Okla. for her questions
What causes the auroras?
The auroras, the Northern Lights and the Southern Lights, came under investigation during the International Geophysical Year. New information was gathered by teams of scientists and by satellites. Whatts more, the auroras themselves seemed eager to help. During the IGY, there was more aurora razzle dazzle than usual. The old explanation of the auroras, has however, has not been scrapped. The research of the IGY/merely added more information and. given a fuller explanation,
Scientists have known for a long time that the shimmering lights were caused by charged particles from the sun. The displays always come a day or two after a solar flare up. They knew, too, that the showy activity occurs between 60 and 600 miles above the earth. They also knew that the displays center near the north and south polar regions because of the influence of the earth’s magnetic field.
These simple facts were proved to be true. But the new information showed that the entire story was far from simple. The cause of the auroras is very complex indeed. The most important new factor was discovered early in the IGY. Our satellites discovered belts of charged atomic particles high above the earth. They are called the Van Allen belts in honor of the head of the U.S, team that discovered them.
An aurora display begins with a flare up on the sun. Clouds of energetic atomic particles pour forth into space. Some 92 million miles away is the solid earth, a magnet surrounded by a vast magnetic field. Clouds of the particles speeding from the sun become trapped in the earth’s magnetic field. Some 10$000 miles above the planet, they meet the outer Van Allen belt, a huge doughnut of proton and electron particles. Here their paths are swerved by lines of magnetic force.
Clouds of the visiting particles, we are told, are swerved around towards one of the earth’s magnetic poles. Here they get a boost which bounces them back along lines of magnetic force to the opposite pole. Back they bounce again and again. Some of the particles fail to swing with this see saw. They fall or dip down towards the earth’s magnetic poles. These energetic proton and electron particles crash into atoms of oxygen and nitrogen high in the atmosphere. In the collisions. X rays are given off as are the shimmering colors of the auroras.
The glimmering blue and the vibrant red of the aurora are caused by atomic collisions 600 miles above the ground. Streamers, arcs and shimmering curtains of hazy green occur 60 and 150 miles above the ground. The halos of ghostly yellow and the wavy ribbons of primrose are blended from the higher level reds and the lower level greens and sandwiched between them.