Plasma plumes protect Earth from dangerous solar storms, according to a new three-dimensional map.
The Earth's magnetic field is generated deep within our planet, and expands out into space, until it hits the solar wind. As the Sun radiates particles into space, they create a breeze-like effect, which gives the solar wind its name.
An effect called "magnetic reconnection" can take place when the magnetic field of the Earth meets up with field lines from the Sun. This can cause extreme magnetic storms to come down toward our planet. These disruptions can affect satellites, spacecraft and even airplanes.
Researchers investigated why the storms did not traverse the atmosphere as often as calculations predicted. They discovered low-energy plasma, formed into a plume, that crosses magnetic field lines.
"The Earth's magnetic field protects life on the surface from the full impact of these solar outbursts. Reconnection strips away some of our magnetic shield and lets energy leak in, giving us large, violent storms. These plasmas get pulled into space and slow down the reconnection process, so the impact of the sun on the Earth is less violent," John Foster, associate director of MIT's Haystack Observatory, said.
Philip Erickson, from the Haystack Observatory, as well as Brian Walsh and David Sibeck of the Goddard Space Flight Center led the research.
Plasma plumes have been studied for over a decade using GPS-TEC. This technique studies signals sent from GPS satellites, and received by more than 1,000 receivers on Earth. Large magnetic storms can often disrupt those waves. By measuring the interference, astronomers are able to determine the concentration of plasma seen in different parts of the sky. This method is only able to produce two-dimensional maps.
In order to create a three-dimensional model, researchers had to map from space. Fortunately, when Foster asked Walsh about the idea, most of the work was already done. In January 2013, a moderate solar storm struck the Earth. According to the earlier data, a plasma plume met the resulting magnetic disturbance.
When the researchers checked trajectories of three satellites measuring auroras, they found each of them passed through the point where the magnetosphere met the plasma.
Analysis of the data showed how plasma behaved like a river and was able to alter the direction of magnetic storms. Foster compared the process to the Gulf Stream, directing currents.
Once in the atmosphere, this plasma can "flow through a huge circulation system, with a lot of different consequences. What these types of studies are showing is just how dynamic this entire system is," Foster said.
Study of the effect of plasma in the magnetosphere was detailed in the journal Science.