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A Public Outreach Module:
Solar Wind, Genesis, and the Planets

How does Solar Max affect the Earth's magnetosphere?

Electromagnetic radiation from the flares arrives at Earth in about eight minutes and can cause severe disruptions in the Earth's upper atmosphere, where the radiation is absorbed. It takes about 70 hours for the CME particles and its associated magnetic shock wave to arrive at Earth.

In periods of intense solar activity, CMEs can compress the Earth's magnetosphere. CMEs that travel faster than the low-speed solar wind produce leading shock waves and force energetic protons (H+) into the Earth's radiation belt where they remain for weeks or months following the passage of the shock front through the magnetosphere. Others work their way back out into the magnetosheath and are lost to space.

A small number of charged solar wind particles reach the Earth's atmosphere. If these particles strike gaseous atoms and molecules in the Earth's atmosphere, they excite them. When the atoms and molecules "de-excite", they emit bright colored light at high altitudes. We call this phenomenon the auroras, or the Northern and Southern Lights. This is one of the visible effects of the Solar Max on the Earth's atmosphere.

In 1997, a CME produced an enormous magnetic cloud and an interplanetary shock wave that hit the Earth's magnetosphere on January 10, shortly after midnight, Universal Time. The shock was followed about 24 hours later by some unusually high-density solar wind—150 particles/cm3, approximately 15 times the average solar wind density—that greatly compressed the magnetosphere. This strong pressure pulse was followed by a solar wind stream traveling at approximately 600 km/s, which is higher than average speed. There was also a rapid buildup of energetic electrons inside the Earth's inner magnetosphere that disrupted electrical power grids.

Solar-related atmospheric disturbances can disrupt long range, short-wave radio communications because these short waves bounce off the bottom of the ionosphere as they are propagated from one point to another. High-frequency radio communications are also affected by Solar Max activity, especially in polar regions and high latitudes, because Earth's magnetic lines are more concentrated closer to the magnetic poles.

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For a more technical description, take a Closer Look at
The Structured Sun and Solar Max: At the Core of the Matter.