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:
“Coming together again after a long day apart can be an experience where joy, relief, anger, and fatigue are all present in different degrees both for the parent and for the child. Because of their importance in marking the resumption of direct contact, reunions deserve as much attention and care as separations to enhance the relationship between parent and child.”
—Alicia F. Lieberman (20th century)
“The importance of a lost romantic vision should not be underestimated. In such a vision is power as well as joy. In it is meaning. Life is flat, barren, zestless, if one can find one’s lost vision nowhere.”
—Sarah Patton Boyle, U.S. civil rights activist and author. The Desegregated Heart, part 1, ch. 19 (1962)
“One’s condition on marijuana is always existential. One can feel the importance of each moment and how it is changing one. One feels one’s being, one becomes aware of the enormous apparatus of nothingness—the hum of a hi-fi set, the emptiness of a pointless interruption, one becomes aware of the war between each of us, how the nothingness in each of us seeks to attack the being of others, how our being in turn is attacked by the nothingness in others.”
—Norman Mailer (b. 1923)