Solar wind interactions

Solar wind interactions with the ionosphere and magnetosphere cause short-term fluctuations in Earth's geomagnetic field

Geomagnetic storms

Solar activity

Geomagnetic storms are often caused by solar activity, such as solar flares and coronal mass ejections

K-index

The intensity of geomagnetic storms is measured using indices like the K-index

Auroras

Solar wind interactions with Earth's magnetic field can also lead to the formation of auroras

Geodynamo processes

Longer-term changes in Earth's geomagnetic field are driven by geodynamo processes in the liquid outer core

Secular variation

Secular variation describes the slow and continuous change in Earth's geomagnetic field over decades to centuries

Magnetic field decay

The axial dipole component of Earth's magnetic field has been weakening at an average rate of about 5% per century

Reversals

Geomagnetic reversals occur when the positions of the magnetic poles switch, leaving a record in volcanic and sedimentary rocks

Excursions

Geomagnetic excursions are shorter-lived disturbances in the magnetic field's orientation that do not result in a full reversal

Frequency

The frequency of reversals and excursions is irregular, with intervals ranging from tens of thousands to millions of years

Remanent magnetization

Earth's magnetic history is preserved in minerals like magnetite, which acquire a remanent magnetization at the time of their formation

Paleomagnetic studies

Paleomagnetic studies use data from rocks and artifacts to reconstruct the history of Earth's geomagnetic field

Geomagnetic polarity time scale

The geomagnetic polarity time scale is a tool used to date geological and archaeological materials based on changes in Earth's magnetic field