SPACE — Earth is the only one in the solar system, because of him
unique for a number of reasons. Earth is the only planet with a breathable oxygen atmosphere, covered in liquid water, and is the only celestial body known to harbor life.
However, an often overlooked characteristic that makes our planet special is that it is the only rocky body in the inner solar system that has strong magnetic poles. Because your compass will be useless on Mars.
Where do these poles come from, and what do they do? To answer that question, let’s start by stripping the center of our beloved planet.
The earth’s core is divided into two layers; a solid inner core and an outer core made of liquid metal. Both layers are made from a mixture of magnetic iron and nickel, with small amounts of light elements such as oxygen, silicon and sulfur.
The inner core is extremely dense and hot, like a giant incandescent marble. However, the outer core is liquid and rotates around the solid mass with its own convective currents. “It is this constant convection that produces the Earth’s magnetic field,” said John Tarduno, a geophysicist at the University of Rochester New York to Live Science, Monday, September 11 2023.
When heat from the inner core continuously radiates to the outer core, it encounters material that is cooled by plate tectonic activity. This cycle drives convection, giving rise to a so-called geodynamo that produces a magnetic field.
Other planets, such as Mars and Venus, do not have magnetic fields, partly due to the lack of plate tectonics. Evidence suggests that the planets may have once had self-sustaining geodynamos, but then disappeared for unknown reasons. Mercury does have a magnetic field, but it is too weak, only 1.1 percent of Earth’s magnetic field, so it is unable to protect the planet from solar radiation.
When liquid metal in Earth’s outer core flows, its movement and high iron content cause the planet to act like a huge dipolar magnet. One pole is negatively charged and the other is positively charged. About 80 percent of the Earth’s magnetic field is organized this way, but the remaining 20 percent is non-dipolar. “Instead of forming parallel bands of magnetic force, there are certain regions where the magnetic field rotates and continues to rotate, behaving like a hovering weather pattern,” Tarduno said.
These irregular patterns produce strange spots in the magnetic field, places like the South Atlantic Anomaly, a large region of the Atlantic Ocean where the intensity of the Earth’s magnetosphere drops drastically. Researchers think this ‘dent’ in the magnetic field arises from unusual tectonic activity beneath Africa. Areas like the South Atlantic Anomaly are interesting, but also concerning, for several reasons.
“The magnetosphere is like a protective covering,” said Joshua Feinberg, a geologist specializing in paleomagnetism at the University of Minnesota.
This magnetosphere helps deflect large amounts of harmful solar radiation away from Earth, acting like a layer of sunscreen across the planet. In areas where the magnetosphere is weak, additional doses of radiation can leak, potentially contributing to high rates of skin cancer.
“Another concern is the impact on satellites,” Tarduno said.
A burst of solar radiation, which we know as a coronal mass ejection, can paralyze satellites and other spacecraft if they are not protected by the Earth’s magnetic field. This could have disastrous impacts on telecommunications, internet access, and GPS services in areas affected by the anomaly.
The South Atlantic anomaly may be 11 million years old, according to a 2020 paper published in the journal PNAS. The anomaly is thought to be related to other planetary magnetic field phenomena, such as pole reversal.
2023-09-12 12:21:00
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