Sun spewed a two million mile per hour stream of charged particles toward the invisible
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magnetic fields surrounding Earth, known as the magnetosphere on April 5, 2010. As the particles interacted with the magnetic fields, the incoming stream of energy caused stormy conditions near Earth. Some scientists believe that it was this solar storm that interfered with commands to a communications satellite, Galaxy-15, which subsequently foundered and drifted, taking almost a year to return to its station. So to better understand how to protect satellites from intense bursts of energy from the sun, scientists study the full chain of space weather events from first eruptions on the sun to how the magnetic fields around Earth compress and change shape in response. During the April 5 storm, two NASA Heliophysics System Observatory missions, the Interstellar Boundary Explorer (IBEX) and two spacecraft called the Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS), were perfectly positioned to view the storm from complementary viewpoints. The three sets of instruments have been used together to paint a more complete picture of what happens during a solar storm, from initial impact of solar energy through to the particles that ultimately slide down into Earth’s atmosphere near the poles. The two TWINS spacecraft and IBEX orbit Earth in very different paths. TWINS travels along a highly elliptical orbit around Earth through the magnetosphere. IBEX, too, circles Earth, but generally lies outside the magnetosphere allowing it to map the very edges of the solar system. Together, they offer glimpses from the inside and outside of the magnetosphere, including the side that faces the sun, the side that extends long away from the sun ,the magnetotail, and an electric current that sometimes appears around Earth like a giant hula hoop called the ring current. The ENA images from IBEX were taken from a distance of around 180,000 miles above the magnetosphere. They show that the magnetosphere immediately compressed under the impact of the charged particles from the solar wind. Minutes later, one of the TWINS spacecraft observed changes in the inner magnetosphere from a much-closer 28,000 miles: the ring current began to trap incoming charged particles. About 15 minutes after impact, these trapped particles gyrated down magnetic field lines into Earth’s atmosphere, a process known as “precipitation.” The time delay between the onset of trapped particles and losing them to the atmosphere points to a fairly slow set of internal processes carrying the region from storm impact through compression to precipitation.