Question 15

Just a piece of info from wiki poorly formed into a question.Nevertheless, here goes:The XY is a torus of energetic charged particles (plasma) around Earth, which is held in place by Earth's magnetic field. This field is not uniformly distributed around the Earth. On the sunward side, it is compressed because of the solar wind, while on the other side it is elongated to around three earth radii. This creates a cavity called the Chapman-Ferraro Cavity, in which the XY resides. It is split into two distinct Y, with energetic electrons forming the outer Y and a combination of protons and electrons creating the inner Y. In addition, the Y contain lesser amounts of other nuclei, such as alpha particles. The XY are closely related to the Z phenomenon where particles strike the upper atmosphere and fluoresce.Prior to the Space Age, the possibility of trapped charged particles had been investigated by Kristian Birkeland, Carl Stormer, and Nicholas Christofilos.The existence of the X was confirmed by the Explorer 1 and Explorer 3 missions in early 1958, under Dr James X at the University of Iowa. The trapped radiation was first mapped out by Explorer 4, Pioneer 3 and Luna 1.The term XY refers specifically to the surrounding Earth; however, similar Y have been discovered around other planets. The Sun does not support long-term Y.

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Answer:The Van Allen radiation belt, related to the polar aurora.