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Stars have areas
of magnetic activity. The heavy magnetic activity
areas produce what are known as starspots.
Starspots are similiar to the sunspots from our
own stellar body. The significance of sunspots to
Earths climate is great and, for this reason,
astronomers have taken to studying starspots on
stars other than our own Sun. |
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A Solar Flare
like this one, is a manifestation of magnetic
activity on the sun |
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The
Harvard-Smithsonian Center for Astrophysics
predicts that the Sun may decline in brightness
during the next century. This is because the
magnetic activity will decrease and the Sun will
dim. A similiar event, called the Little Ice Age,
occured in the 17th Century. Astronomers now
refer to this period as the Maunder Minimum. The
chart below shows the starspot activity on Earth
for the past few centuries. The relatively flat
time between 1645 and 1715 is the Maunder
minimum. |
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The number of starspots
on the sun varies in 11 year cycles and in 300
year cycles |
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You'll notice that
approximately every 11 years the number of spots
on the sun cycles. Through carbon dating, a
second trend of a decrease in magnetic activity
every has been identified. During low magnetic
activity periods, more carbon is produced in the
Earth's upper atmosphere by cosmic rays from deep
space. This carbon (C14) turns up in plantlife.
Through testing the carbon in the tree rings of
7,00 year old bristlecone pines, the amount of
magnetic activity can be ascertained. Researchers
found that approximately every three-hundred
years their was a "minimum" like that
in the second half of the 17th century. That three hundred year mark is
approaching during the next century. The actual
drop in temperature may be 2 degrees Farenheit or
1 Degree Celcius in the next 50 years.
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