Blurs

Earth has a magnetic field that stretches far into space, protecting the planet from much of the charged radiation streaming from the Sun. Most people know the basic explanation: movement of molten, electrically conductive material in Earth's outer core generates the geodynamo responsible for the main magnetic field. But Earth's magnetism is considerably more complicated than that. The field measured at Earth's surface is actually a combination of several magnetic sources. One comes from deep within the planet. Another comes from magnetised rocks in the crust. Others are generated by electrical currents in the ionosphere and magnetosphere. And there is a particularly intriguing component that sometimes gets described as Earth's "second magnetic field." It isn't a second planet-sized dynamo hidden inside Earth. But it reveals just how dynamic our magnetic environment really is. The Main Magnetic Field Earth's dominant magnetic field is generated in the ...

A compass seems like one of the simplest instruments ever invented. A needle points north. You follow it. You arrive where you intended to go. But there is a complication. The needle doesn't actually point towards the geographic North Pole. It responds to Earth's magnetic field—and that field is constantly changing. Across much of the planet, the difference is small enough to ignore. In certain places, however, magnetic anomalies can become surprisingly strong. A compass may deviate from the direction you expect, behave strangely near magnetic rocks, or point significantly away from geographic north. Earth is not simply a giant magnet. It is a complicated magnetic machine. Geographic North Isn't Magnetic North The first thing to understand is that there are two different "norths". Geographic north is the direction towards the Earth's rotational North Pole. Magnetic north refers to the direction indicated by a magnetic compass. The two are separated by hundreds...

The Magnetic Dent NASA Monitors: Understanding the South Atlantic Anomaly Invisible to the human eye, an unusual region of weakened magnetism stretches across much of South America and the South Atlantic Ocean.  Known as the South Atlantic Anomaly (SAA), it is often described as a "dent" or "dip" in Earth's magnetic shield. Although it poses no danger to people on the ground, it presents a significant challenge for satellites and spacecraft, prompting continuous monitoring by NASA and other space agencies. Far from being a sign of impending catastrophe, the South Atlantic Anomaly is a natural feature of Earth's ever-changing magnetic field. Its existence provides scientists with valuable clues about the dynamic processes occurring thousands of kilometres beneath our feet. Geodynamo: Earth's Magnetic Shield Earth behaves like a giant magnet because of the movement of molten iron and nickel within its liquid outer core, approximately 2,900 kilometres benea...