Реферат: Aurora Borealis Essay Research Paper Near the
Aurora Borealis Essay, Research Paper
Near the Earth’s poles a magnificent spectacle of shimmering colored light can sometimes be seen — the aurora. The aurora is called the aurora borealis (Northern lights) and the aurora austrails (Southern lights); it can appear as bright as a full moon. The aurora usually appears near the Earth’s poles, and more northerly (or southerly) your latitude, the more impressive the displays you will see. The lights vary in color from whitish-green to deep red and take on shapes such as streamers, arcs, curtains, and shells. But we still don’t know what causes them. Lets find out.
Aurorae are produced when charged particles from the sun enter the Earth’s atmosphere. This stream of particles, a form of plasma, is carried away from the sun by the solar wind. As the plasma approaches Earth, it is trapped for a time in the outermost parts of the Earth’s magnetic field, an area called the Van Allen belts. Eventually the plasma is drawn down toward the North and South magnetic poles. Along the way, it ionizes (creates an electric charge within) the oxygen and nitrogen gas it encounters in the atmosphere, causing it to glow. The flow of plasma from the sun is generally continuos, although it occasionally bursts out of holes in the sun’s outermost atmosphere. Massive ejections of plasma have also been shown to accompany solar flares, prominences, and sunspots. It is during these periods of highest solar activity that one is most likely to witness aurorae.
The aurora is an ideal subject for the amateur astronomer because no telescope or any other optical apparatus is needed for observing it. It also makes a good subject for anyone who can draw or paint. This beautiful display of lights is one of the most amazing things that the night sky has to offer.