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	Sunspot - Wikipedia, the free encyclopedia
		As of 2006, we are near the minimum (predicted for 2007) in the sunspot cycle [1].
		Sunspot research was dormant for much of the 17th and early 18th centuries because of the Maunder Minimum, during which no sunspots were visible for some years; but after the resumption of sunspot activity, Heinrich Schwabe in 1843 reported a periodic change in the number of sunspots.
		At the start of a cycle, sunspots tend to appear in the higher latitudes and then move towards the equator as the cycle approaches maximum: this is called Spörer's law.
	en.wikipedia.org /wiki/Sunspot_cycle (1798 words)

	Scientists Issue Unprecedented Forecast of Next Sunspot Cycle - News Release
		BOULDER—The next sunspot cycle will be 30-50% stronger than the last one and begin as much as a year late, according to a breakthrough forecast using a computer model of solar dynamics developed by scientists at the National Center for Atmospheric Research (NCAR).
		The forecasts are generated, in part, by tracking the subsurface movements of the sunspot remnants of the previous two solar cycles.
		The NCAR team's computer model, known as the Predictive Flux-transport Dynamo Model, draws on research by NCAR scientists indicating that the evolution of sunspots is caused by a current of plasma, or electrified gas, that circulates between the Sun's equator and its poles over a period of 17 to 22 years.
	www.ucar.edu /news/releases/2006/sunspot.shtml (851 words)

	Summary of Panel Findings (Site not responding. Last check: 2007-10-14)
		The general trend in recent solar activity cycles (Figure 1) is toward larger amplitude sunspot cycles; Cycle 19 was the largest in recorded history (smoothed sunspot number maximum of 201 in March, 1958), and Cycle 22 was the third largest (smoothed maximum of 159 in July, 1989).
		Cycles 21 and 22 both showed annual averages of geomagnetic activity that were large in comparison with most cycles in the record of aa indices (Figure 2).
		While all cycles have multiple-maxima, even-numbered cycles tend to have a broad maximum late in the declining phase of the solar activity cycle attributed to a favorable orientation of the solar dipole (positive polarity in the northern solar hemisphere) which is oppositely directed to Earth's dipole field.
	www.sel.noaa.gov /info/Cycle23.html (2548 words)

	The Sunspot Cycle (Site not responding. Last check: 2007-10-14)
		One striking feature that emerges from the long-term data is that the number of sunspots observed in a given year varies in a dramatic and highly predictable way.
		If one plots the total number of sunspots observed in a year as a function of the year the plot shown to the right is obtained.
		There is a striking variation in the number of sunspots that is cyclic, with a period of approximately 11 years.
	csep10.phys.utk.edu /astr162/lect/sun/sscycle.html (205 words)

	Sunspots: Modern Research 4 of 7
		In the last few decades, the forces behind sunspots are becoming better understood, but we've known for over a 150 years that sunspots appear in cycles.
		The part of the cycle with low sunspot activity is referred to as "solar minimum" while the portion of the cycle with high activity is known as "solar maximum."
		As the sunspot cycle progresses, the visible sunspots move gradually towards the equator.
	www.exploratorium.edu /sunspots/research4.html (336 words)

	Sunspot -- from Eric Weisstein's World of Astronomy
		Sunspots may affect Earth's climate, as deduced from the low number present during the little ice age of 1640-1710.
		During a solar cycle, all sunspot pairs in the northern hemisphere have the leading spot north and the trailing spot south (it is reversed in the southern hemisphere).
		The variation over the solar cycle was observed to be 0.04% between 1980 and 1986, when the flux at the Earth (known as the solar constant declined from 1368.5 to 1367 W m
	scienceworld.wolfram.com /astronomy/Sunspot.html (394 words)

	Dr. SOHO's FAQ: Sunspots and the Solar Cycle (Site not responding. Last check: 2007-10-14)
		A typical sunspot temperature is about 3500 degrees Celsius, instead of the 6000 degrees C of the adjacent regions of the photosphere (the visible surface of the Sun).
		The region around a sunspot group where the strong magnetism dominates the motion of gases in the solar atmosphere is usually referred to as an active region.
		Those latitudes change with the sunspot cycle: The first spots in a solar cycle (what we are seeing now, in early 1997) appear around 30 degrees North or South of the equator.
	sohowww.nascom.nasa.gov /explore/faq/sunspots.html (3051 words)

	NSO/EO: Mr. Sunspot's Answer Book: Sunspots (Site not responding. Last check: 2007-10-14)
		Sunspots are darker than the rest of the visible solar surface because they are cooler: Most of the visible surface of the Sun has a temperature of about 9700 F (5400 C), but in a big sunspot the temperature can drop to about 7200 F (4000 C).
		The differential rotation of the Sun (the variation of rotation period with latitude) is thought to be the cause of the solar cycle, the variation in the activity level of the Sun as measured, for instance, by the number of sunspots.
		Sunspots do not affect human behavior, for the same reasons that they do not affect the weather: they are too small and too far away.
	eo.nso.edu /MrSunspot/answerbook/sunspots.html (4918 words)

	Timo Niroma: Sunspots: 5. The 200-year sunspot cycle is also a weather cycle
		The Gleissberg cycle is usually cited with one of two values, accurately as 78 years, inaccurately as 80 years, but the 200-year cycle has no agreed-upon value, mostly the values referred to are from 180 to 220 years.
		Explicitly there is no 200-year cycle in the Elatina data, but I have interpreted that the 29.2 "sawtooth pattern" represents a cycle of 173 years, which means that it may be a variant of the 200-year cycle.
		Since the ongoing cycle is the 13th cycle since the last long cycle in 1784-1867 this cycle is should reverse the trend, which means a long cycle probably ending somewhere in 2009-2010.
	personal.inet.fi /tiede/tilmari/sunspot5.html (3727 words)

	Sunspots: Modern Research 4 of 7 (Site not responding. Last check: 2007-10-14)
		By studying the sun's magnetic field, modern astronomers have discovered that the cycle covers twenty-two years, with each eleven-year cycle of sunspots followed by a reversal of the direction of the Sun's magnetic field.
		Sunspots appear mostly in the low latitudes near the solar equator.
		The sunspot locations for the most recent 11-year cycle are shown in this "butterfly" diagram." The locations "migrated" toward the equator (0 latitude) from both hemispheres throughout this half of the cycle.
	cse.ssl.berkeley.edu /segwayed/lessons/sunspots/research4.html (377 words)

	NGDC/STP - Sunspot Numbers
		Wolf chose to compute his sunspot number by adding 10 times the number of groups to the total count of individual spots, because neither quantity alone completely captured the level of activity.
		Wolf, who became director of the Zurich Observatory, discovered independently the coincidence of the sunspot cycle with disturbances in the earth's magnetic field.
		The cycle, though, is not symmetrical, for the spot count takes on the average about 4.8 years to rise from a minimum to a maximum and another 6.2 years to fall to a minimum once again.
	www.ngdc.noaa.gov /stp/SOLAR/SSN/ssn.html (420 words)

	A SLEEPIER SUNSPOT CYCLE? (Site not responding. Last check: 2007-10-14)
		A decline in sunspots, which can cause power flouts and exacerbate global warming, is likely in the next 10 years according to a Yale and NASA astronomers' report delivered Tuesday, Jan. 14, at a meeting of the American Astronomical Society in Toronto.
		Sunspots are dark areas that appear on the sun periodically and were first observed by Galileo in the early 1600s.
		Sunspots can play havoc with satellites, too, because the ultraviolet radiation they release causes atmospheric resistance that can make satellites slow down and come back to earth earlier than planned.
	www.businessweek.com /bwdaily/dnflash/january/new0114d.htm (335 words)

	ScienceDaily: Groundbreaking Research To Improve Forecasts Of Sunspot Cycle (Site not responding. Last check: 2007-10-14)
		Sunspots also become increasingly powerful with the progress of the solar cycle because the continuous shearing of the imprints of the magnetic fields by the denser plasma beneath the surface of the Sun increases the strength of the spot-producing magnetic fields.
		Sunspot -- A sunspot is a region on the Sun's surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity.
		Carbon cycle -- The carbon cycle is the biogeochemical cycle by which carbon is exchanged between the biosphere, geosphere, hydrosphere and atmosphere of the...
	www.sciencedaily.com /releases/2004/05/040531212256.htm (2226 words)

	The sunspot cycle (Site not responding. Last check: 2007-10-14)
		The number of sunspots visible on the solar disk at any given time varies continuously, as sunspots are carried on and off the visible disk by solar rotation.
		Proxies of geomagnetic activity such as aurorae (green crosses) correlate well with the sunspot number, in the sense that lower auroral counts are associated with low amplitude sunspot cycles (e.g., 1940 - 1960), and high counts with high amplitude cycles (1800 - 1822).
		Remembering that sunspots are associated with magnetic fields, it is tempting to assume that the sunspot cycle is primarily magnetic in origin.
	www.agu.org /history/sv/contrib/Maunder.html (607 words)

	Sunspot Cycle Predictions
		Predicting the behavior of a sunspot cycle is fairly reliable once the cycle is well underway (about 3 years after the minimum in sunspot number occurs [see Hathaway, Wilson, and Reichmann Solar Physics 151, 177 (1994)]).
		Relationships have been found between the size of the next cycle maximum and the length of the previous cycle, the level of activity at sunspot minimum, and the size of the previous cycle.
		He found a relationship between the number of days during a sunspot cycle in which the geomagnetic field was "disturbed" and the amplitude of the next sunspot maximum.
	www.llansadwrn-wx.co.uk /cache/Sunspotcyclepredictions.htm (864 words)

	NASA - Scientists Gaze Inside Sun, Predict Strength of the Next Solar Cycle
		Sunspots and stormy solar weather follow the eleven-year cycle, from few sunspots and calm to many sunspots and active, and back again.
		Key to predicting the solar activity cycle is an understanding of the flows of plasma in the sun's interior.
		The next cycle will begin with a rise in solar activity in late 2007 or early 2008, according to the team, and there will be 30 to 50 percent more sunspots, flares, and CMEs in cycle 24.
	www.nasa.gov /centers/goddard/news/topstory/2006/solar_cycle.html (928 words)

	13March 1989 - Solar CME Storm
		There were two other sunspots that covered around 5,000 milllionths of the solar disk: one in 1946 (the year after fission bombs were dropped on Japan) and one in 1951 (the year that fusion bombs were first exploded).
		A sunspot around 3,500 millionths of the solar disk was associated with the 13 March 1989 Solar Flare.
		Sunspots are sources of intense magnetic knots that spiral outwards even as the dipole field vanishes.
	www.valdostamuseum.org /hamsmith/13Mar89.html (6983 words)

	Spaceflight Now \| Breaking News \| Powerful 'conveyor belts' drive Sun's 11-year cycle
		NASA and university astronomers have found evidence the 11-year sunspot cycle is driven in part by a giant conveyor belt-like, circulating current within the Sun.
		Monthly sunspot averages show that the number of sunspots visible on the Sun waxes and wanes with an approximate 11-year cycle.
		The circulation is faster in cycles shorter than the average 11-year period and slower in cycles longer than the average period.
	spaceflightnow.com /news/n0306/25solarcycle (609 words)

	Sunspots
		Note, however, that the "Sunspot Number" referred to in these graphs is not a count of sunspots, but rather a number adjusted to take into account the number of groups visible, the number of individual spots visible, and differences between observers.
		Relationships have been found between the size of the next cycle maximum and the length of the previous cycle, as well as the level of activity at sunspot minimum and the size of the previous cycle.
		Galileo was not the first to observe sunspots (the Chinese earned that distinction thousands of years before), but Galileo was the first to study sunspots and their movements through a telescope.
	solar-center.stanford.edu /about/sunspots.html (531 words)

	Sunspots and Activist Strategy
		Sunspots are solar explosions, as big as 50,000 miles across, which appear as dark blotches on the surface of the sun.
		Considering that during a period of maximum sunspot activity there may be as many as 200 solar flares in one year, as compared with as few as five during a year of minimum activity, it is not surprising that all these atmospheric disruptions might similarly disrupt human sensibilities.
		That sunspot cycle activity increased and decreased in a cycle of approximately 11 years was established in the 1750s.
	www.carolmoore.net /articles/sunspot-cycle.html (2877 words)

	Space Today Online -- The Sun and the Solar System -- Sunspots
		Sunspots can be seen to vary on the face of the Sun in eleven-year actvity cycles.
		The sunspots gave NASA an exasperating choice -- launch Hubble so high a shuttle might not be able to reach it for repair, or launch it so low shuttles would have to fly every six months to boost it higher.
		During the sunspot peak in 1989, a blast of solar energy arriving at Earth shut down the electrical power grid in the Canadian province of Quebec, leaving six million customers in the dark for a day.
	www.spacetoday.org /SolSys/Sun/Sunspots.html (1574 words)

	The Sun and Stellar Structure
		Hundreds of years of observing the sunspots on the Sun shows that the number of sunspots varies in a cycle with an average period of 11 years.
		At the start of a sunspot cycle the number of sunspots is at a minimum and most of them are at around 35° from the solar equator.
		In one 11-year cycle the leading sunspot in a sunspot group will have a north magnetic pole while the trailing sunspot in the group will have a south magnetic pole.
	www.astronomynotes.com /starsun/s2.htm (2166 words)

	Mount Wilson Observatory
		For the most part, the rise time of a sunspot cycle is shorter than the decay time, and sometimes, for example circa AD 1790 the decay is prolonged.
		The shape of the sunspot cycle seems to be linked to the height; cycles which rise rapidly generally have higher maxima (for example compare the cycles from the 1960's and 1970's).
		In Figure 8, individual cycles are overlayed (the gridmarks are one year in the x direction and 20 in sunspot number on the y axis).
	www.mtwilson.edu /hk/ARGD/Sunspot_Cycle (1400 words)

	The Sunspot Cycle
		The Sunspot Cycle was discovered in 1843 by the amateur German astronomer Samuel Heinrich Schwabe.
		Between 1700 and today, the sunspot cycle (from one solar min to the next solar min) has varied in length from as short as nine years to as long as fourteen years.
		Sunspots show us where the Sun's magnetic field might be "twisted up" enough to cause solar flares and coronal mass ejections.
	www.windows.ucar.edu /tour/link=/sun/activity/sunspot_cycle.html (464 words)

	Solar cycles 21, 22 and 23 (Site not responding. Last check: 2007-10-14)
		The red line is the monthly smoothed sunspot number while the blue line is the actual monthly sunspot number.
		Cycle 21 started in June 1976 with a smoothed sunspot number of 12.2.
		Cycle 23 started in May 1996 with the monthly SSN at 8.0 and peaked in April 2000 at 120.8.
	www.dxlc.com /solar/solcycle.html (112 words)

	Sunspot Cycle Closely Following Prediction
		The sun now is on the upswing of its 23rd activity cycle, a numbering scheme that dates from the mid-19th century, although the sunspot cycle may have lasted as long as the sun has burned.
		What is now called the International sunspot number or the Zurich number is a blend of actual numbers of individual spots and numbers of groups of spots on the sun.
		Because the solar magnetic fields reverse at the peak of each 11-year cycle, solar activity cycle actually spans a 22-year "Hale cycle." Cycle 23 is the last half of the current Hale cycle (composed of Cycles 22 and 23) that began in 1986.
	www.eurekalert.org /pub_releases/1998-10/NSFC-SCCF-191098.php (563 words)

	Space Today Online -- The Sun and the Solar System -- Sunspot Cycle 23 Twin Peaks
		Solar scientists have calculated that the Sun reached the solar maximum of the latest eleven-year sunspot activity cycle in the month of April 2000 when the smoothed sunspot number (SSN) was 120.8.
		Cycle 20 took about four years to reach peak and about seven uears to descend to minimum.
		An additional indication that Cycle 23 peaked in the year 2000 came in a NASA report in February 2001 that the Sun's magnetic field had flipped.
	www.spacetoday.org /SolSys/Sun/SunspotsTwinPeaks.html (587 words)

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