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:
“We ought to esteem it of the greatest importance that the fictions which children first hear should be adapted in the most perfect manner to the promotion of virtue.”
—Plato (c. 427–347 B.C.)
“The importance to the writer of first writing must be out of all proportion of the actual value of what is written.”
—Elizabeth Bowen (1899–1973)
“More than ten million women march to work every morning side by side with the men. Steadily the importance of women is gaining not only in the routine tasks of industry but in executive responsibility. I include also the woman who stays at home as the guardian of the welfare of the family. She is a partner in the job and wages. Women constitute a part of our industrial achievement.”
—Herbert Hoover (1874–1964)