World's top 10 fascinating natural phenomena

13:13, November 20, 2009      

Email | Print | Subscribe | Comments | Forum 

1. The Northern Lights



The Northern Lights occur when the sun gives off high-energy charged particles (also called ions) that travel out into space at speeds of 300 to 1,200 kilometers per second. A cloud of such particles is called plasma. The stream of plasma coming from the sun is known as solar wind. As the solar wind interacts with the edge of the earth's magnetic field, some of the particles are trapped and they follow the lines of magnetic force down into the ionosphere, the section of the earth's atmosphere that extends from about 60 to 600 kilometers above the earth's surface.
【1】 【2】 【3】 【4】 【5】 【6】 【7】 【8】 【9】 【10】

  • Do you have anything to say?
http://english.people.com.cn/90001/90782/6819179.pdf