News 32009

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The Sun has re-lighted itself

THE SUN OBSERVED IN THE 22ND MAY 2008

Restlessness is over. The Sun has re-lighted itself according to the rules and everything has re-entered in the normalcy and a new cycle is about to begin. The Sun returns therefore to perform, as in the past the objectives of the satellites American Trace, Japanese Hinode and European SOHO of the ESA have documented. Last Saturday a spot (number 1005) marked its surface and it was the third one in three weeks; this means an indication of

a resumption of the activity. The sunspots, observed for the first time by Galileo Galilei in 1611, are areas with a lower temperature than photosphere and this is enough to make them darker for contrast. They are always associated with strong magnetic fields. This activity involves us because the phenomenon of the spots comes together with flows of radiations and particles that then invest the Earth causing, when they are particularly intense, the geomagnetic storms on our planet; this means troubles and troubles to the satellites in orbit, to the systems of communication and the electric nets. It’s already happened and the cause is documented. THE SUN WITH A CLOUD OF PLASMA The new spots mark the conclusion of the period of quietness that the star was crossing in its eleven year periodic cycle in which a moment of maximum activity followes one of minimum. The various solar cycles have had, obviously, different characteristics: some have been calm others more intense. The next one that is coming is anticipated as moderated according to the experts of the Space Weather Prediction of the National Oceanic and Atmospheric Administration. Moderate, nevertheless, it has a very relative meaning because spots and eruptions, recorded by the satellites, have SUNSPOT SEEN TO WAVELENGTH H-ALPHA dimensions that can contain a lot of

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History of Science and Technology

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European Pupils Magazine

times our planet. So we can understand the power of the phenomenons and the worry that their effects can sometimes create to the life on the Earth. But also to the astronauts that firmly sojourn by now on the spatial station. They are the first ones to be exposed and to suffer possible consequences. Comment This article is about the Sun and his "awakening" from the minimum grade of activA GREAT SOLAR EXPLOSION ity that has almost characterized it for the whole year 2008, beating different records of least precedents and arousing worry among the researchers, that affirmed that if the solar minimum had still continued there would have been a cooling of the Earth. Actually it is not really correct to say that the Sun is recovering from the minimum activity, in fact in the preceding days some stains are observed, probably of the new cycle and an upsurge of the solar wind, but the solar radiation has now returned on very low values; this shows that the Sun is not definitely recovered and that the solar miniDETAIL BROUGHT CLOSER OF THE MAGNETIC STRUCTURE OF THE mum could still persist. SOLAR SURFACE OBSERVED TO WAVELENGTH H-ALPHA •

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Bibliography Giovanni Caprara, Il Sole si è riacceso, Il Corriere della Sera, www.corriere.it/ scienze_e_tecnologie/08_ottobre_14/sole_attività_acb7f302-99ff-11dd-a6f300144f02aabc.shtml, RCS Quotidiani Spa, Milan, 14/10/2008 Iconography Images 01-05: Giovanni Caprara, Il Sole si è riacceso, Il Corriere della Sera, www.corriere.it/scienze_e_tecnologie/08_ottobre_14/sole_attività_acb7f302-99ff-11dda6f3-00144f02aabc.shtml, RCS Quotidiani Spa, Milan, 14/10/2008

Federico Pedicona

Liceo Boggio Lera Catania, Italy [email protected]

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