June 11, 2014
Earth’s Magnetosphere Doesn’t Stop All Solar Wind From Breaking Through
Brett Smith for redOrbit.com - Your Universe Online
Using data from four European Space Agency satellites that fly in formation in the Earth's magnetic field, researchers have uncovered new information on how the solar wind can break through the Earth’s magnetosphere and disrupt modern life.
According to a new report in the journal Physical Review Letters, when the solar wind meets the environment around the Earth – an electromagnetic phenomenon called an asymmetric magnetic reconnection takes place.
Magnetic reconnections can give energy to activity on the solar surface and can change the energy from the incoming solar wind so that it creates what we see in an aurora. These reconnections are also a major stumbling block when it comes to storing energy through processes in fusion reactors.
If two colliding fields of plasma have the same density, temperature and strength, but distinct orientations of their magnetic fields, symmetrical reconnection commences. In more usual instances, two plasma fields have distinct characteristics, for instance when the solar wind reaches the Earth.
The study team used data from the ESA’s Cluster satellites to try and understand this scenario.
"Especially important were measurments with two satellites only a few tens of kilometres from each other, in the region where the solar wind meets the Earth's magnetic field," said study author Daniel Graham, from the Swedish Institute of Space Physics (IRF). "We can thus do detailed measurements to understand plasma physics at a height of 60,000 km."
The researchers said they are particularly interested in the heating of electrons parallel to the magnetic field in conjunction with magnetic reconnection.
"We believe that this is an important piece of the puzzle for understanding how magnetic reconnection works, how charged particles are accelerated, and how particles from different regions can be mixed with each other," Graham said. "Our detailed measurements in the Earth's magnetic field can be used to understand the physics even in fusion reactors on Earth, and in far distant regions in space that we can't reach with satellites."
A study published last month found the solar wind can be highly influential when it comes to electrical storms here on Earth.
Published in the journal Environmental Research Letters, that study revealed a considerable raise in lightning rates throughout Europe in the 40 days following the arrival of high-speed solar winds, which can move at over a million miles per hour from the Sun.
“Our main result is that we have found evidence that high-speed solar wind streams can increase lightning rates. This may be an actual increase in lightning or an increase in the magnitude of lightning, lifting it above the detection threshold of measurement instruments,” said study author Chris Scott, a space and atmospheric physics professor at the University of Reading.
He added that cosmic radiation, as well as particles created by our own Sun, affects lightning activity.
“We propose that these particles, while not having sufficient energies to reach the ground and be detected there, nevertheless electrify the atmosphere as they collide with it, altering the electrical properties of the air and thus influencing the rate or intensity at which lightning occurs,” Scott said.