Researchers identify driver for near-Earth 11 December 2006

New findings indicate that the and other The team of researchers studied NASA satellite near-Earth space weather are driven by the rate at observations of global auroral activity, NOAA which the Earth’s and ’s magnetic fields satellite observations of the stretching of the connect, or merge, and not by the solar wind’s Earth’s magnetic field lines on the Earth’s electric field as was previously assumed. nightside, and Air Force satellite observations of the access of solar wind particles to the Earth’s The merging occurs at a spot between the Earth upper atmosphere. They questioned whether the and Sun, roughly 40,000 miles above the planet’s electric field activity was really the best predictor, or surface, and appears fundamental to the if each phenomenon would require its own formula, circulation of particles and magnetic fields and were surprised to learn that a single throughout near-Earth space. formula—for the merging rate—gave the best clues to the behavior of these 10 aspects of space weather. Researchers at the Johns Hopkins University Applied Laboratory (APL) in Laurel, Md., Professors George Siscoe of and and the Air Force Research Laboratory at Stanley Cowley of Leicester University had Hanscom Air Force Base (Massachusetts) will previously suggested that the merging rate would announce the results of their study at the Fall better explain near-Earth convection, but Newell American Geophysical Union Meeting in San and his colleagues were surprised at how well the Francisco on Dec. 11. The researchers, led by single new formula works. Patrick Newell of APL, have developed a formula that describes the merging rate of the magnetic For a space scientist, the work is interesting also field lines and predicts 10 different types of near- because it provides the first strong empirical Earth space weather activity, such as the aurora estimate of the global merging rate. Boston and magnetic disturbances. University’s Siscoe says of the study, “It clearly represents a massive amount of work, and it is “Having this formula is a big step forward for undoubtedly an important contribution to the understanding how the sun and Earth interact,” subject of solar wind- coupling. says Newell. And that understanding could help People will probably be discovering further predict the space weather that affects implications of the formula for years.” communications, navigation, and the health of humans in space. Source: Johns Hopkins University

The space between the Earth and Sun is not empty, but filled with energetic particles, most of which are generated in the solar atmosphere. Temperatures of a few million degrees accelerate a stream of these particles, called the solar wind, to roughly 1 million miles per hour. Space weather scientists had long assumed that near-Earth space weather phenomena could best be predicted by the behavior of the solar wind electric field. However, Newell and his colleagues were the first to put this theory to a rigorous test with many data sets from a number of years.

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APA citation: Researchers identify driver for near-Earth space weather (2006, December 11) retrieved 27 September 2021 from https://phys.org/news/2006-12-driver-near-earth-space-weather.html

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