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)
“There is much to be said in favour of modern journalism. By giving us the opinions of the uneducated, it keeps us in touch with the ignorance of the community. By carefully chronicling the current events of contemporary life, it shows us of what very little importance such events really are. By invariably discussing the unnecessary, it makes us understand what things are requisite for culture, and what are not.”
—Oscar Wilde (1854–1900)
“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)