A ring current is an

electric current An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge c ...

carried by charged particles trapped in a planet's

magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...

. It is caused by the longitudinal drift of energetic (10–200 k eV) particles.

Earth

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

's ring current is responsible for shielding the lower latitudes of the Earth from magnetospheric electric fields. It therefore has a large effect on the electrodynamics of

geomagnetic storm A geomagnetic storm, also known as a magnetic storm, is a temporary disturbance of the Earth's magnetosphere that is driven by interactions between the magnetosphere and large-scale transient Plasma (physics), plasma and magnetic field structur ...

s. The ring current system consists of a band, at a distance of 3 to 8 ''R''_E, which lies in the equatorial plane and circulates clockwise around the Earth (when viewed from the north). The particles of this region produce a magnetic field in opposition to the

Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...

and so an Earthly observer would observe a decrease in the

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

in this area. The negative deflection of the Earth's magnetic field due to the ring current is measured by the Dst index. The ring current energy is mainly carried around by the ions, most of which are protons. However, one also sees alpha particles in the ring current, a type of ion that is plentiful in the solar wind. In addition, a certain percentage are O⁺ oxygen ions, similar to those in the ionosphere of Earth, though much more energetic. This mixture of ions suggests that ring current particles probably come from more than one source.

Geomagnetic storms

During a

, the number of particles in the ring current will increase. As a result, there is a decrease in the effects of geomagnetic field.

References

* Geophysics Space science Space plasmas {{geophysics-stub

Earth

Geomagnetic storms

See also

References