SOLAR CYCLE
WHAT IS A SUNSPOT?
Sunspots are darkregions that appear on the
"surface" of the Sun.
 Sunspots are "dark" because they are cooler
than their surroundings.
 A large sunspot might have a central
temperature of 4,000 K (about 3,700° C or
6,700° F), much lower than the 5,800 K (about
5,500° C or 10,000° F) temperature of the
photosphere
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HOW BIG IS A SUNSPOT?
HOW BIG IS A SUNSPOT?
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Sunspots are very large structures. Although they look small
against the backdrop of the Sun, which has a diameter of
1.4 million km (870 thousand miles), most sunspots could
swallow a planet.
Many sunspots, like the ones shown in the image, are as
large as Earth!
Most spots range in size from about 1,500 km (932 miles) to
around 50,000 km (31,068 miles) in diameter. Occasionally
gigantic sunspots the size of Jupiter appear on the Sun's
"surface".
Astronomers believe some other stars also have spots.
Young stars seem especially likely to have large numbers of
starspots, and some of those may be immense.
WHAT IS THE SOLAR CYCLE
WHAT IS THE SOLAR CYCLE
The observations of sunspots
 Sunspots are not constant (due to rotation,
new one form, old ones fade away)
 Sunspots occur in an eleven year cycle
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 Reflects
the 22 year cycle for the reversal of the
sun’s magnetic field.
 The migration of the sunspots has a butterfly effect
STUDYING THE SOLAR CYCLE
In 1848 Johann Rudolf devised a method of
counting sunspots on the solar disc called the
Wolf Number (averaged from many observing
sites)
 The cycle appears to be uniform this century;
however, in 1645-1715 there was few sunspots
present ( Maunder Minimum)
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WHY IS THERE A SOLAR CYCLE?
No one knows the answer to this question
 A detailed explanation of the solar cycle is a
fundamental physics problem waiting to be
solved.
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SOLAR CYCLE VARIATIONS AND EFFECT ON
EARTH’S CLIMATE
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For more than 100 years scientists have
wondered if cycles on the sun and solar
irradiance (or energy) received at Earth
because those cycles affect weather or global
climate on Earth.
SOLAR CYCLE VARIATIONS AND EFFECT ON
EARTH’S CLIMATE
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It is now thought that the solar cycle does not
play affect weather, but they do have a slight
effect on global climate ( but not enough to
explain recent global warming)
MAUNDER MINIMUM AND ITS EFFECT ON
EARTH’S CLIMATE
This was the largest well-documented
disruption in sunspots observed in history
 Europe and parts of North America were struck
by spells of remarkably cold weather at roughly
the same time.
 The “Little Ice Age” extended from 1350-1850,
and some of its coldest periods coincide with
times of decreased sunspots
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ACTIVITY: PLOTTING/GRAPHING SUNSPOTS
Follow the directions on the worksheet-BUT
ONLY PLOT YEARS 1926- 2007
 Make sure to answer all the questions on a
separate piece of paper.
 For question #2a- only do 1926-present NOT
1700s- present
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