NASA Explores Earth's Magnetic "Dent"

Narration: Katie Jepson

Transcript:

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Above South America, a weak spot in Earth’s

magnetic field is evolving.

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Called the South Atlantic Anomaly, this unique

region has

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been expanding for more than a decade.

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And scientists believe that it’s beginning

to split into two distinct zones.

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Now, while this anomaly poses little risk

to life here on Earth, it does allow scientists

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to study the complicated mechanisms behind

Earth’s magnetism.

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Around 1800 miles below the surface, dynamic

processes in Earth’s liquid iron outer core

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are continuously generating electrical currents.

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This account for the majority of Earth’s

magnetic field.

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But unlike a typical bar magnet, with one

north and south pole, Earth’s magnetism

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isn’t all neat and tidy.

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If we take a look below the anomaly at the

boundary separating the core and the mantle,

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we can see the magnetic variations are much

stronger.

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This picture provides a clear link between

the anomaly we see in Earth’s magnetosphere,

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its origins deep within Earth’s interior,

and

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how it is projected to evolve in the near future.

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This is important to understand, because our

planet’s magnetic field plays a huge role

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in shaping the near-Earth environment.

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In addition to guiding compasses and animal

migrations, the magnetic field acts like a

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shield, repelling charged particles flung

from the Sun that

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could be disruptive if they reached the surface.

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Many of the particles that do slip inside

Earth’s protective bubble become trapped

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in large rings of energetic particles called

the Van Allen Belts, which are held in place

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by Earth’s magnetic field.

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The inner edge of the innermost belt is about

400 miles from the surface of Earth at the

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equator, which keeps particle radiation a

safe distance

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from Earth and orbiting satellites.

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But because of the offset between Earth’s

magnetic and rotational poles, and the weakened

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magnetic field over Southern Atlantic Anomaly,

some energetic particles within the belts

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penetrate closer to the Earth's surface.

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This means that NASA and other space agencies

need to account for the extra radiation when

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low-orbit satellites pass through the anomaly.

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Currently, NASA researchers are using data

from satellites, along with theoretical models,

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to track the evolution of the South Atlantic

Anomaly, and help prepare for future challenges

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to managing satellites and humans in space.

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