The Earth's magnetic field is the original forcefield, a wall of electromagnetic force that protects us from high-energy charged particles spewed by our sun during solar eruptions. The dance between our field and the sun is dynamic and beautiful.

Charged particles impacting on the magnetic field produce aurora. Image credit: N. Tsyanenko

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The solar wind is a highly conductive plasma. The high electrical conductivity transports magnetic field lines, building a magnetic field between the sun and planets in our solar system. The core of our planet is a geomagnetic dynamo, its iron-rich liquid outer core generating a planetary magnetic field. The field is complex and constantly changing in response to internal dynamics, but also gets blown around by the interplanetary magnetic field.

Nikolai Tsyganenko used a cluster of European Space Agency satellites to make detailed observations on how the magnetic field changes over time. Tsyganenko used the data to create a set of three animations modelling the impact of the interplanetary magnetic field on the Earth's protective magnetic shell.

Case 1: Axis vs Wind

The orientation of the Earth's magnetic axis with respect to the direction of the solar wind changes based on the diurnal and annual rotation of the Earth. Side gusts of solar wind can produce a similar effect. This change in orientation produces a wiggle in in the field, waggling back and forth like a flag in the wind.

Case 2: Impact of the Solar Wind

A steady state solar wind produces is a regular impact on the magnetic field of the Earth. The red spikes at the magnetic poles are prime locations for aurora-watching. This smooth field is one of those rarely-realized theoretical ideals: gusts in the solar wind make reality more complicated.

Case 3: Gusts in the Solar Wind

Gusts in the solar wind produce dramatic changes in the Earth's field, squeezing and flaring the magnetosphere's tail. During a magnetospheric storm, the dayside of the field temporarily compresses while extending the tail. Eventually the nightside field collapses in a substorm, leading to the field gradually settling back to its pre-storm status.

Read more on the European Space Agency cluster website.