| Stardust storms heading for solar system Until ten years ago, most astronomers did not believe stardust could enter our Solar system. Then the European Space Agency’s (ESA) Ulysses spaceprobe discovered minute stardust particles leaking through the Sun's magnetic shield. Now, the same spaceprobe has shown that a flood of dusty particles is heading our way, potentially threatening satellite communications systems by causing physical damage to equipment and coating solar panels, thus reducing power generation capabilities. Since its launch in 1990, Ulysses has constantly monitored how much stardust enters the solar system from the interstellar space around it. Using an on-board instrument called DUST, scientists have discovered that stardust can actually approach the Earth and other planets, but its flow is governed by the Sun's magnetic field, which behaves as a powerful ‘gate-keeper’, bouncing most of it back. However, during solar maximum - a phase of intense activity inside the Sun that marks the end of each 11-year solar cycle - the magnetic field becomes disordered as its polarity reverses. As a result, the Sun's shielding power weakens and more stardust can sneak in. What is surprising in this new Ulysses discovery is that the amount of stardust has continued to increase even after the solar activity calmed down and the magnetic field resumed its ordered shape in 2001. Scientists believe that this is due to the way in which the polarity changed during solar maximum. Instead of reversing completely, flipping north to south, the Sun's magnetic poles have only rotated at halfway and are now more or less lying sideways along the Sun's equator. This weaker configuration of the magnetic shield is letting in two to three times more stardust than at the end of the 1990s. Moreover, this influx could increase by as much as ten times until the end of the current solar cycle in 2012. The stardust itself is very fine - just one-hundredth of the width of a human hair. It is unlikely to have much effect, but it is bound to collide with asteroids, chipping off larger dust particles. Astronomers still do not know whether the current stardust influx, apart from being favoured by the particular configuration of the Sun's magnetic field, is also enhanced by the thickness of the interstellar clouds into which the solar system is moving. Currently located at the edge of what astronomers call the local interstellar cloud, our Sun is about to join our closest stellar neighbour Alpha Centauri in its cloud, which is less hot but denser.
•Date:
26th August 2003 • Region: Worldwide•Type:
Article •Topic: Telecoms
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