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QUIET SUN:
Today marks the 44th consecutive day without spots on the sun--one
of the longest quiet spells of the current solar minimum. In early
July, sunspot
1024 seemed to herald the long-awaited onset of Solar Cycle
24, but shortly after that apparition, sunspot production turned
off again. Deep solar minimum continues...
ARE SUNSPOTS DISAPPEARING?
Sunspots are made of magnetism. The "firmament"
of a sunspot is not matter but rather a strong magnetic field that
appears dark because it blocks the upflow of heat from the sun's
fiery depths. Without magnetism, there would be no sunspots.
That's what makes the following graph a little troubling:
According to Bill Livingston and Matt Penn of the National Solar
Observatory in Tucson, Arizona, sunspot magnetic fields are waning.
The two respected solar astronomers have been measuring solar magnetism
since 1992. Their technique is based on Zeeman
splitting of infrared
spectral
lines emitted by iron atoms in the vicinity of sunspots. Extrapolating
their data into the future suggests that sunspots could completely
disappear within decades. That would be a bummer for Spaceweather.com.
Don't count out sunspots just yet, however. While the data of Livingston
and Penn are widely thought to be correct, far-reaching extrapolations
may be premature. This type of measurement is relatively new, and
the data reaches back less than 17 years. "Whether this is
an omen of long-term sunspot decline, analogous to the Maunder Minimum,
remains to be seen," they caution in a recent
EOS article.
One thing is certain. Solar Minimum is a lot more interesting than
it sounds: more.
JUPITER UPDATE:
A little more than a month after a mystery-object
crashed into Jupiter, the debris cloud is still visible in backyard
telescopes. Amateur astronomer Brian Combs of Buena Vista, Georgia,
took this picture on August 19th:
When Australian astrophotographer Anthony Wesley discovered
the debris cloud on July 19th, it was about the size of many other
small storms dotting Jupiter's upper atmosphere. Since then, the
compact black mark has expanded into an enormous swirl rivaling
the girth of the Great Red Spot itself. Unfortunately, as the cloud
has expanded it has also faded, and its pale markings could soon
disappear altogether. Continued monitoring is encouraged.
more images: from
Abe Megahed of Madison, Wisconsin; from
Ralf Vandebergh of the Netherlands
August
2009 Aurora Gallery
[previous Augusts: 2008,
2007, 2006,
2005, 2004,
2003, 2002,
2001]
2009
Perseid Photo Gallery
[Science@NASA: The
Perseids are Coming, Horse
Flies and Meteors]
Explore
the Sunspot Cycle
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