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Sun-Earth Connection Continued Sun-Earth Connection
The sun produces the light that makes life on earth possible. It also emits dangerous ultraviolet radiation, which can cause skin cancer. Periodically, the sun kicks out high-energy particles, solar flares, and CMEs that can knock out power grids and interfere with communications, navigation systems, and electronic components on satellites and other spacecraft. As society becomes more dependent on technology, from high-frequency radio communication to satellite telephones, Internet, and navigation systems, we are more vulnerable to disruptions from CMEs. For instance, in January 1997, AT&T lost contact with its Telstar 401 satellite. In March 1989, the entire province of Quebec suffered a nine-hour blackout when currents from a geomagnetic storm developed in transmission wires and knocked out a major power grid. To make matters worse, we're going from a period when magnetic activity on the sun is at a low point, the so-called "solar minimum," to one in which we can expect lots more flares, CMEs, and geomagnetic storms. CMEs occur about once a week during solar minimum and up to twice or more a day at solar maximum. Solar flares average one or less per day during solar minimum and up to several a day during solar maximum. This increased activity could cause problems for astronauts as they build the international space station.
To better understand and predict the effects of CMEs on the earth's upper atmosphere and magnetosphere, scientists from the University of Maryland have developed a computer model of a powerful geomagnetic storm that arrived on January 10, 1997. In the simulation, the magnetic cloud from the sun smacks the magnetosphere with a burst of plasma thirty times denser than the normal solar wind. When high-energy particles from the CME reach earth's magnetic fields, says astrophysicist Charles Goodrich, they produce "a storm of killer electrons moving at the speed of light and generating millions of electron volts of energy." International Effort to Study the Sun
The solar scientists highlighted above are part of HESSI and the International Solar Terrestrial Physics (ISTP) program, a comprehensive effort to observe and understand the sun and its effects on earth. NASA, the European Space Agency (ESA), and Japan's Institute of Space and Astronautical Science (ISAS) are collaborating with scientists from 18 countries and more than 100 institutions to build our understanding on the sun-earth connection . |
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