Earth's magnetic field
Protects Earth from solar wind and enables navigation.
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind. It is generated by electric currents due to the motion of convection currents of a mixture of molten iron and nickel in Earth's outer core, a natural process called a geodynamo. The field deflects most of the solar wind, protecting Earth from charged particles that would otherwise strip away the upper atmosphere, including the ozone layer.
- field
- Geophysics, Paleomagnetism
- known_for
- Deflecting solar wind, enabling compass navigation, recording magnetic reversals in rocks
- dipole_tilt
- Approximately 11° with respect to Earth's rotational axis
- pole_migration
- North Magnetic Pole moves up to 40 km per year; has migrated northwestward over the last 180 years
Lore & Background
Earth's magnetic field is generated by convection currents of molten iron and nickel in the outer core, driven by heat escaping from the core. It is approximated as a magnetic dipole tilted about 11° from the rotational axis, as if a bar magnet were placed at that angle through Earth's center. The North geomagnetic pole (on Ellesmere Island, Nunavut, Canada) actually represents the South pole of Earth's magnetic field, because opposite magnetic poles attract and a compass needle's north end points toward Earth's South magnetic field.
Reader's Guide
The significance of Earth's magnetic field lies in its role as a protective shield and a navigational aid. It deflects most of the solar wind, whose charged particles would otherwise strip away the ozone layer that protects Earth from harmful ultraviolet radiation. Calculations of the loss of carbon dioxide from Mars's atmosphere indicate that the dissipation of its magnetic field caused a near total loss of its atmosphere. The field also records its own history: reversals of the geomagnetic poles leave a record in rocks, valuable for paleomagnetists in calculating past geomagnetic fields and studying the motions of continents and ocean floors. Humans have used compasses for direction finding since the 11th century A.D. and for navigation since the 12th century. Various organisms, from bacteria to pigeons, use magnetoreception for orientation and navigation.
Did You Know?
- The North geomagnetic pole (on Ellesmere Island, Nunavut, Canada) actually represents the South pole of Earth's magnetic field.
- At irregular intervals averaging several hundred thousand years, Earth's field reverses and the North and South Magnetic Poles abruptly switch places.
Frequently Asked Questions
Who is Earth's magnetic field?
Earth's magnetic field is the invisible magnetic shield that stretches from the planet's molten outer core out into space, where it meets the solar wind. It is produced by the churning of liquid iron and nickel in the outer core, a process geologists call the geodynamo.
What are Earth's magnetic field's powers/role?
Its primary job is deflecting the charged particles of the solar wind away from the planet, shielding the upper atmosphere and ozone layer from being stripped away. It also gives compass needles a direction to align with, enabling magnetic navigation.
How does Earth's magnetic field's story end?
It has no fixed ending—the field is in constant motion, with the North Magnetic Pole drifting up to 40 km per year in a northwestward trend over the past 180 years. Rocks also record full magnetic reversals, so the narrative keeps rewriting itself across geological time.
Why is Earth's magnetic field important?
Without it, the solar wind would erode the upper atmosphere and destroy the ozone layer, leaving surface life far more exposed to harmful radiation. It also underpins paleomagnetism, allowing scientists to read the magnetic history locked into ancient rock formations.
More in Geology 1-24
Elsewhere in the Geology universe
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record