Along a radial cut of the plasma coming inward from the Sun near the dayside sub-solar point, the solar wind and magnetosheath flow is high-beta, the magnetopause
and immediate (thin) plasma boundary provides a high to low beta transition, and immediately within the low-latitude boundary layer (within the outer magnetosphere) plasma is low-beta.
is located between 1000 and 2000 km from the planet's surface (on average at 1.
Once it reaches the outer magnetosphere, the author says, the plasma can be lost to the solar wind, either crossing through the magnetopause
or being swept down the magnetotail.
Magnetic reconnection at the Earth's magnetopause
is the mechanism by which magnetic fields in different regions - in this case, from the Interplanetary Magnetic Field (IMF) carried by the solar wind, and the Earth's magnetic field - change topology to open magnetospheric field lines.
In the study, a NASA satellite called IMAGE (Imager for Magnetopause
to Aurora Global Exploration) observed two powerful proton auroras in the arctic portion of Earth's upper atmosphere, or ionosphere.
Previous discoveries derived from Cluster measurements have shown that the magnetopause
is commonly subject to Kelvin-Helmholtz waves.
A moderate geomagnetic storm was induced by this geoeffective CME after the shock hit the Earth, shrinking the subsolar magnetopause
from ~10 Earth radii to ~6.
In half an hour, this high-pressure wave travelled more than a million kilometres (620,000 miles) to the Earth's magnetopause
defines the boundary between the Earth's field and the solar wind.
From March 20 to April 20, 2002, sensors on board NASA's Imager for Magnetopause
to Aurora Global Exploration (IMAGE) satellite recorded these bands, which glow in ultraviolet light.
They also identified the magnetospheric region that corresponds to these emissions, and by analogy with similar flares on Earth, they determine that the flares are probably related to pulsed reconnections of the magnetic field at the planet's dayside magnetopause
(boundary where the planet's magnetic field meets the solar wind of particles flowing from the Sun).
The boundary separating Earth's magnetic sphere of influence from the solar wind is called the magnetopause