Ja tinha lido isso acerca destes "profetas da desgraça"...Parece que cada vez que existe alguma coisa fora dos padrões conhecidos, vai logo acabar o mundo!!1<div>73 de CT4RK</div><div><br><br><div class="gmail_quote">
2009/9/7 João Gonçalves Costa <span dir="ltr"><<a href="mailto:joao.a.costa@ctt.pt">joao.a.costa@ctt.pt</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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<p><font face="Verdana"><span><a href="http://www.norcalblogs.com/watts/images/sunspots_earth_size_big.jpg" target="_blank"><img style="float:left;margin:0pt 0pt 10px 10px;width:200px" alt="" src="http://www.norcalblogs.com/watts/images/sunspots_earth_size_big.jpg" border="0"></a> </span></font></p>
<div style="text-align:left"><span></span>
<div style="text-align:justify"><span>William Livingston e Matt
Penn, investigadores do Observatório Nacional Solar – Tucson: EUA - dizem que o
nosso Sol, a partir de 2015, poderá perder as suas manchas solares, denotando
menos actividade, o que poderá levar a uma nova pequena idade do gelo - como no
Maunder Minimum (Mínimo de Maunder), entre 1645 e 1715 quando a actividade de
manchas solares reduziu-se drasticamente, gerando na Terra uma redução dramática
da temperatura. </span><span>No continente europeu e América do
Norte registraram-se temperaturas baixíssimas, provocando o congelamento de
grandes cursos de rios que normalmente não passam por essa situação.
</span><span></span><span>O nome
“Maunder” deve-se ao astrónomo inglês E. W. Maunder (1851-1929) do
Observatório de Greenwich, que o relatou quando estudava os
registos históricos sobre o Sol</span></div></div>
<div>
<div style="text-align:left">
<div style="text-align:justify">
<div></div>
<div></div></div></div></div></span><strong><font size="6">Are sunspots disappearing?</font></strong></div>
<p><font face="Verdana"><strong>Nasa</strong> report that the sun is in the pits
of the deepest solar minimum in nearly a century. Weeks and sometimes whole
months go by without even a single tiny sunspot. The quiet has dragged out for
more than two years, prompting some observers to wonder, <em><strong>are
sunspots disappearing?</strong></em></font></p>
<p><font face="Verdana">"Personally, I'm betting that sunspots are coming back,"
says researcher Matt Penn of the National Solar Observatory (NSO) in Tucson,
Arizona. But, he allows, "there is some evidence that they won't."</font></p>
<p><font face="Verdana">Penn's colleague Bill Livingston of the NSO has been
measuring the magnetic fields of sunspots for the past 17 years, and he has
found a remarkable trend. Sunspot magnetism is on the decline.</font></p>
<p><font face="Verdana">While most researchers measure the splitting of spectral
lines in the visible part of the sun's spectrum, Livingston decided to try an
infra-red spectral line. Infrared lines are much more sensitive to the Zeeman
effect and provide more accurate answers. Also, he dedicated himself to
measuring a large number of sunspots—more than 900 between 1998 and 2005 alone.
The combination of accuracy and numbers revealed the downturn.</font></p>
<p><font face="Verdana">"According to our measurements, sunspots seem to form only
if the magnetic field is stronger than about 1500 gauss," says
Livingston.</font></p>
<p><font face="Verdana">"If the current trend continues, we'll hit that threshold
in the near future, and solar magnetic fields would become too weak to form
sunspots."</font></p>
<p><font face="Verdana">"This work has caused a sensation in the field of solar
physics," comments NASA sunspot expert David Hathaway, who is not directly
involved in the research. "It's controversial stuff."</font></p>
<p><font face="Verdana">If sunspots do go away, it wouldn't be the first
time.<br>In the 17th century, the sun plunged into a 70-year period of
spotlessness known as the <em><strong>Maunder Minimum</strong></em> that still
baffles scientists. The sunspot drought began in 1645 and lasted until 1715;
during that time, some of the best astronomers in history (e.g., Cassini)
monitored the sun and failed to count more than a few dozen sunspots per year,
compared to the usual thousands.</font></p>
<p><font face="Verdana">"Whether [the current downturn] is an omen of long-term
sunspot decline, analogous to the Maunder Minimum, remains to be seen,"
Livingston and Penn caution in a recent issue of EOS. "Other indications of
solar activity suggest that sunspots must return in earnest within the next
year."</font></p>
<p><font face="Verdana">Whatever happens, notes Hathaway, "the sun is behaving in
an interesting way and I believe we're about to learn something new."</font></p>
<p><font face="Verdana">Read the full NASA report at</font></p>
<div><a href="http://science.nasa.gov/headlines/y2009/03sep_sunspots.htm?list130845" target="_blank"><font face="Verdana">http://science.nasa.gov/headlines/y2009/<br>03sep_sunspots.htm?list130845</font></a>
<br></div>
<div><font face="Verdana">Fontes: Blog Ano Zero e Southgate Amateur Radio
Club.</font></div>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Best 73 from: regards from: CT4RK Carlos Mourato - Sines - Portugal<br><br> Save the Radio Spectrum! Eliminate Broadband over Power Line. Salve o espectro electromagnético!. Não use a rede electrica para transmitir dados. Os "homeplugs power line" e a tecnologia "power line" causa fortes interferencias noutro serviços sem voce se aperceber. Diga não à tecnologia power line. Proteja o ambiente<br>
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