Importance
The Earth is largely protected from the solar wind, a stream of energetic charged particles emanating from the Sun, by its magnetic field, which deflects most of the charged particles. These particles would strip away the ozone layer, which protects the Earth from harmful ultraviolet rays. Calculations of the loss of carbon dioxide from the atmosphere of Mars, resulting from scavenging of ions by the solar wind, are consistent with a near-total loss of its atmosphere since the magnetic field of Mars turned off.
The polarity of the Earth's magnetic field is recorded in sedimentary rocks. Reversals of the field are detectable as "stripes" centered on mid-ocean ridges where the sea floor is spreading, while the stability of the geomagnetic poles between reversals allows paleomagnetists to track the past motion of continents (the study of past magnetic field is known as paleomagnetism). Reversals also provide the basis for magnetostratigraphy, a way of dating rocks and sediments. The field also magnetizes the crust; magnetic anomalies can be used to search for ores.
Humans have used compasses for direction finding since the 11th century A.D. and for navigation since the 12th century.
Read more about this topic: Earth's Magnetic Field
Famous quotes containing the word importance:
“There are of course people who are more important than others in that they have more importance in the world but this is not essential and it ceases to be. I have no sense of difference in this respect because every human being comprises the combination form.”
—Gertrude Stein (1874–1946)
“Think of the importance of Friendship in the education of men.... It will make a man honest; it will make him a hero; it will make him a saint. It is the state of the just dealing with the just, the magnanimous with the magnanimous, the sincere with the sincere, man with man.”
—Henry David Thoreau (1817–1862)
“Kitsch is the daily art of our time, as the vase or the hymn was for earlier generations. For the sensibility it has that arbitrariness and importance which works take on when they are no longer noticeable elements of the environment. In America kitsch is Nature. The Rocky Mountains have resembled fake art for a century.”
—Harold Rosenberg (1906–1978)