6520 South 190th Street
Kent, Washington 98032
Sun Sportswear is recognized for its ability to attract retail shoppers' interests. We accomplish this by offering a well-designed product line and fresh, attractive artwork that sells our screen printed goods.
History of Sun Sportswear, Inc.
The largest producer of silkscreened apparel in the United States, Sun Sportswear, Inc., designs, sources, prints, markets, and sells an extensive collection of imprinted, dyed, and decorated casual sportswear for men, women, and children. During the mid-1990s, Sun Sportswear sold its proprietary and licensed designs to roughly 30 national and regional chains, including Wal-Mart, Target Stores, K-Mart, Montgomery Ward, JC Penney, and Sears. The company conducted its business by purchasing blank T-shirts, sweatshirts, sweatpants, tank tops, nightshirts, and similar apparel items and screenprinting designs on those garments. For its licensed designs, the company owned the rights to use or distribute certain characters and trademarks that included "Looney Tunes," "Major League Baseball," "Pocahontas," "The Lion King," "101 Dalmatians," "Garfield," "Batman Forever," and "Winnie the Pooh." For its proprietary designs, Sun Sportswear relied on concepts developed by its merchandising staff and internal graphics design department.
Founded in 1981
In March 1981, David A. Sabey, Richard Lentz, and James A. Contini entered into business together with the establishment of Sun Sportswear's predecessor, Sun Shirts, Inc., a small firm that began business as a T-shirt designer in suburban Seattle, Washington. From the company's founding date forward, Sabey and his successors steered Sun Sportswear in new directions by adding product lines, penetrating new markets, and redefining the company's business strategy. The changes initiated transformed the modestly sized, T-shirt designer into the largest producer of silkscreened casual sportswear in the United States in little more than a decade. Absent from the proceedings that marked the rise of the company they had helped found were Lentz, founder of Union Bay Sportswear, and Contini, a graphic artist. Before Sun Sportswear's inaugural year of business was through, Sabey bought out his partners and assumed full control over the company. Under Sabey's stewardship, the whirlwind of changes that shaped Sun Sportswear into the preeminent leader in its industry ensued.
Initially, Sun Sportswear contracted with other manufacturers to supply screenprinted tops to coordinate with pants sold through Lentz's Union Bay Sportswear. With Lentz's departure and the arrival of three hand presses in 1982, however, the scope of the business changed. Beginning in 1982, the company operated by creating its own designs, screenprinting those designs on blank T-shirts purchased from outside sources, and selling the garments to small, regional retail chains, gift and surf shops, and mass merchandisers, deriving nearly all of its business from sales to male customers. A decade later, Sun Sportswear's business would be dramatically different, as a series of pivotal, evolutionary steps transformed the company into a proprietary and licensed designer of casual sportswear for massive retail chains that drew the bulk of its business from female customers. The first important step toward this end was taken in 1983 when the company expanded beyond T-shirts and started to become more of a full-line sportswear company, changing its name from Sun Shirts, Inc. to Sun Sportswear, Inc. to reflect this change. Concurrent with this significant diversification, the company resolved to develop a customer base comprising mass merchandisers and forego the practice of distributing T-shirts to small retail chains, gift shops, and surf shops. Sabey and his executive staff decided to develop long-term relationships with mass merchandisers such as Target Stores and Wal-Mart who operated retail outlets on a nationwide basis. The decision to eschew smaller retailers and target the country's largest mass merchandise chains was a significant one in Sun Sportswear's history, paving the way for the high-volume, low-cost casual sportswear designer the company would eventually become.
By the mid-1980s, Sun Sportswear was gradually making its way toward becoming a contender in the national market for silkscreened garments, having altered it business strategy meaningfully during its first half decade of existence. The company purchased undecorated apparel items from domestic and foreign producers and then, through its internal art staff, created designs that were applied to the garments at Sun Sportswear's production facility in Redmond, Washington. Operating as such, the company existed exclusively as a proprietary designer, scoring its greatest success with its creation of "Rude Dog" in 1986, by which time Sun Sportswear had expanded its production capabilities to include five hand presses and five automatic presses. Initially, "Rude Dog" was emblazoned as a character on T-shirts, but as the popularity of the Sun Sportswear-created figure grew enormously after its introduction, "Rude Dog" appeared on a plethora of items, including skateboards, beach towels, and socks.
By the end of the 1980s, the "Rude Dog" character had turned into a valuable revenue-generating engine of its own, enjoying such widespread popularity that the apparel items decorated by Sun Sportswear could not satisfy consumer demand. The character was licensed to other manufacturers as a result, appearing on 21 different types of consumer products and giving Sun Sportswear a welcomed yet unanticipated boost to its business. Despite the phenomenal success of "Rude Dog" as a licensed character, Sun Sportswear's most important move in the market for licensed products came not as a licensor but as a licensee. For the first six years of its existence, Sun Sportswear derived all of its business from designs created by its own team of artists, with "Rude Dog" ranking as the biggest success. In 1987, however, the company added licensed designs to its product line and opened the door to a lucrative market that in less than half a decade would account for roughly half of its total sales volume. The decision to produce and sell licensed designs stood as a watershed development in the company's history, equalling the significance of the diversification beyond the T-shirt market and the development of a mass merchandiser customer base in 1983.
1987 Entry into Licensed Designs
Sun Sportswear's entry into the licensed design arena was effected in August 1987, when one of the company's largest customers, Wal-Mart, helped it gain the license for the "California Raisin" characters from Applause Licensing Co., based in Woodland Hills, California. With the highly marketable "California Raisin" characters gracing its casual sportswear garments, Sun Sportswear enjoyed an appreciable increase in sales, convincing Sabey and the company's management that the rewards to be gained in producing licensed designs merited further investment. Other licensed designs entered Sun Sportswear's fold after the "California Raisins" deal was brokered, including "Garfield" the cat and a "Batman" license in 1989, when Wal-Mart and Target Stores suggested Sun Sportswear as a more capable supplier than the previous licensee.
Although the licensed segment of Sun Sportswear's business represented a new and promising avenue of growth for the company, it by no means abandoned its mainstay proprietary design business. By 1988, the company's internal design staff was creating 1,200 designs a year and more than 2,000 designs by the following year, as Sun Sportswear executives strove to beat back the capricious nature of garment designs by flooding markets with a vast and ever-changing product line. By continually adding to and revamping its proprietary product line and by negotiating for licenses for popular characters and trademarks, Sun Sportswear kept moving forward and surpassing competitors, recording encouraging financial growth along the way. Annual sales, which amounted to $28.9 million in 1987, more than doubled the following year to $59 million, as revenues from the recently added licensed line of garments came pouring in and the consistent effort to refreshen the proprietary line paid off in financial gains.
To accommodate the company's rapid growth and the increasing number of customers located east of the Mississippi River, a second production facility was purchased in 1988, when Sun Sportswear acquired a warehousing and manufacturing property in Johnson City, Tennessee. On the heels of this acquisition, the company stood poised for a banner year, its position as one of the country's largest silkscreeners firmly established. Sun Sportwear by this point purchased roughly 65 percent of its blank garments from manufacturers predominately located in the southeastern United States, and the remaining 35 percent were imported, primarily from Pakistan, Portugal, and Costa Rica. Once decorated, either with designs created by the company or with licensed designs, the garments were sold to 30 major mass merchandisers, with K-Mart, Wal-Mart, and Target Stores ranking as the company's three largest customers by far.
Women's and Girls' Apparel Launched in 1989
Perhaps more remarkable than the company's consistent and rapid growth in a market driven by whimsical and fleeting fashion trends was that nearly all of the growth achieved during the 1980s was realized from selling to only half of the American population. Since its inception, Sun Sportswear had relied nearly exclusively on male customers for its business, but in June 1989 another opportunity for growth came about when the company began test marketing apparel items targeted for women and girls. By the end of its first year, the women's and girls' apparel division generated $3 million in sales, a modest contribution when compared with the $73.2 million generated in revenues for the year, but expectations ran high, leading company officials to project that eventually women's and girls' apparel would account for between 25 percent and 30 percent of the company's total sales. In this projection the company was wrong, for during the 1990s, when the sales of men's and boys' apparel began to flag, the women's and girls' division picked up the slack, eventually accounting for nearly 70 percent of Sun Sportswear's total business.
Before Sun Sportswear officials realized the riches they had tapped by targeting female customers, the company made one more significant move in 1989. In October, Sun Sportswear filed with the Securities and Exchange Commission for an initial public offering of 1.7 million shares. The sale of Sun Sportswear stock to the public, which was completed in October, represented 21 percent ownership of the company, with Sabey retaining the remaining percentage of ownership. With the money yielded from the public offering, an amount that was expected to bring in as much as $20 million, Sabey intended to finance Sun Sportswear's recent expansion, including $2 million to purchase new equipment for the company's new office and printing facility located on a 9.6-acre site in Kent. The remainder of the funds were earmarked for repaying loans associated with the acquisition of the Johnson City facility and for future expansion, giving Sun Sportswear some of the financial resources it would need to maintain its leadership role in the decade ahead.
Sun Sportswear entered the 1990s on a strong note. The company's product line of screenprinted knit cotton T-shirts, sweatshirts, sweatpants, shorts, and woven T-shirts generated $73.2 million in sales in 1989, a 24 percent increase over the previous year's total. The acquisition in early 1990 of the apparel licensing rights to use the National Wildlife Federation logo on T-shirts and sweats kept the company moving in a positive direction, but from there things began to sour. As the onset of a national economic recession began to appear in headlines across the country, laggard consumer spending, retail inventory reductions, and the popularity of licensed characters not owned by Sun Sportswear combined to negatively affect the Kent-based company's business. In August 1990, as a result of waning sales, the company trimmed its work force by 126 at its screenprinting plants in Kent and Johnson City. Then in April 1991 the company announced it would suspend screenprinting operations at its Johnson City facility altogether. The company continued to use the Johnson City plant as a warehousing hub, but the production was shifted to the manufacturing facility in Kent, where Sun Sportswear management anxiously awaited the return of more prosperous economic conditions.
More prosperous economic conditions did not arrive soon enough, particularly for Sabey, who found himself mired in serious financial difficulties during the early years of the 1990s. Since the establishment of Sun Sportswear, Sabey had greatly expanded his business interests by acquiring a fashionable department store chain based in the Pacific Northwest called Frederick & Nelson. As Sun Sportswear struggled during the early years of the decade, recording a $517,000 loss in 1992, Sabey's Frederick & Nelson department store chain suffered from more pernicious financial difficulties and slipped into bankruptcy as the recession worsened. The financial troubles of Sun Sportswear's chairman resulted in a new majority owner for the company and the return of more prosperous economic times for the country's largest producer of silkscreened garments.
1993 Resignation of Sun Sportswear's Founder
In January 1993, Sabey transferred to Seafirst Corp. 67.7 percent of Sun Sportswear's shares to pay part of his debt to the Seattle-based bank and announced his resignation as chairman effective January 22, 1993. To replace Sabey, Seafirst selected Larry C. Mounger, a Sun Sportswear director who had joined the company's board in 1991. For Seafirst, Mounger, and Sun Sportswear, the timing was perfect. Less than two weeks before Sabey's resignation was scheduled to take effect, Mounger had sold his family-owned business, Pacific Trail Inc., a 48-year-old outerwear firm founded by his father. Despite the propitious turn of events that made Mounger available to guide the fortunes of Sun Sportwear, Mounger had no intention of becoming the company's chairman and chief executive officer. "I was going to retire, manage my own investments and possibly buy, but not run, a business," Mounger later remembered to a reporter from the Puget Sound Business Journal. "I had no idea in the world when I was closing Pacific Trail that this would happen."
Despite his surprise, Mounger wasted no time in making his presence known at Sun Sportswear. He quickly developed a 100-day strategy for the company and explained his objectives. "Number one, we've got to turn this company around and increase profits in 1993," Mounger explained in a Puget Sound Business Journal interview. "Number two, we've got to grow the top-end and increase our customer base." To achieve these goals, Mounger instituted tougher quality control standards, closed the Johnson City plant, and concentrated the company's focus on its core business of screenprinting. By the end of the year, Mounger could point to tangible proof that the changes undertaken during his watch had worked. After recording a loss of $517,000 for 1992, Sun Sportswear's net income rebounded significantly, jumping to a $2.7 million gain. Sales were up as well, rising from $70.6 million to $104.8 million. For the first time since its initial public offering in 1989, Sun Sportswear entered a new calendar year supported by growth on all fronts.
After Sun Sportswear's president resigned in early 1994, Mounger assumed his post to reign as the company's chairman, chief executive officer, and president. Occupying the company's three top executive positions, Mounger moved resolutely forward in 1994, intent on sustaining the positive momentum built up in 1993. More than $2 million was spent on the latest screenprinting technology, with another $2 million slated for investment in late 1994, giving the company a total of 15 screenprinting presses. With the acquisition of additional presses, Sun Sportswear stood well-positioned for anticipated growth, but 1995 would prove to be a difficult year for the company. Sales were invigorated by the popularity of the company's licensed rights to the "Pocahontas" and "Lion King" characters, but the effects of a strike by major league baseball players caused sales of Sun Sportswear's "Major League Baseball" designs to decline. For the year, sales dipped to $93.9 million and the company plunged once again into the red, recording a $3.7 million loss.
As the company struggled through 1995, a leadership change was effected. Just as quickly as he had arrived, Mounger was gone by October, with the only explanation for his sudden departure coming from a company announcement that Mounger had resigned "to have more time to pursue community service and other personal goals." In Mounger's place, William S. Wiley was selected as president and chief executive officer. Wiley, who had been a consultant to the company's reengineering efforts for the six months prior to his arrival at Sun Sportswear as president and chief executive officer, was charged with guiding the company into the late 1990s and steering it toward consistent profitability. As Wiley and his executive team charted their course for the late 1990s, the one undeniably healthy aspect of Sun Sportswear's business was its women's and girls' apparel division. Since its inception in 1989, the division had developed into a $67-million-a-year business, accounting for nearly 70 percent of the company's total sales in 1995. In February 1996, the women's/girls' and men's/boy's divisions were combined, giving both segments the leadership that had orchestrated the women's and girls' division's robust growth. Structured as such, Sun Sportswear headed toward the late 1990s, intent on maintaining its lead as the largest screenprinting producer in the United States.
Related information about Sun
The central object of our Solar System and the nearest star to
the Earth. Its basic characteristics are: mass
99×1030 kg; radius
696 000 km/432 500 mi; mean density
4 g/cm3; mean rotation period 2 4 days; luminosity
85×1024 J/s. Its average distance from Earth is 150
million km/93 million mi, and on account of this
proximity it is studied more than any other star. The source of its
energy is nuclear reactions in the central core (temperature 15
million K, relative density 155) extending to a quarter of the
solar radius and including half the mass. Our Sun is nearly 5000
million years old, and is about halfway through its expected
life-cycle. Every second it annihilates 5 million tonnes of matter,
to maintain power output of
39 × 1026 watts of energy.otheruses
|Mean distance from
(8.31 minutes at the speed of light)
|Visual brightness (V)
|Mean distance from
orbit around the center of the Galaxy, 20 km/s relative to
average velocity of other stars in stellar
(109 Earth diameters)
(342 Earth diameters)
|30}} kg(332,946 Earths)
|273.95 m s-2
from the surface
|Temperature of corona
|26}} W~9 cd[[cite journal
||title=Atmospheric phenomena before and during
|27]] cd (V band)
|Mean Intensity (Isol)
|7}} W m-2sr-1
(to the ecliptic)
(to the galactic
of North pole[[cite web
||title=Report Of The IAU/IAG Working Group On Cartographic
Coordinates And Rotational Elements Of The Planets And
(19 h 4 min 30 s)
of North pole
(25 d 9 h 7 min 13 s)
The Sun is the star
of our solar
system. The Earth and other matter (including other planets, asteroids, meteoroids, comets and dust) orbit the Sun, which by itself accounts for more than
99% of the solar system's mass. Energy
from the Sun?in the form of insolation from sunlight?supports almost all life on Earth via photosynthesis, and
drives the Earth's climate and weather.
The Sun is sometimes referred to by its Latin name Sol or by its Greek name Helios. Its astrological and astronomical symbol is a circle with a point at its
The sun's history and destiny
The Sun is about 4.6 billion years old and is about halfway
through its main-sequence evolution, during which nuclear fusion
reactions in its core fuse hydrogen into helium. Each second, more
than 4 million tonnes of matter are converted into energy within
the Sun's core, producing neutrinos and solar radiation.
In about 5 billion years, the Sun will evolve into a red giant and then a white dwarf, creating a
nebula in the process. The Sun's magnetic field gives rise to
many effects that are collectively called solar activity,
including sunspots on
the surface of the Sun, solar flares, and variations in the solar wind that carry
material through the solar system. The effects of solar activity on
Earth include auroras at moderate to high latitudes, and the
disruption of radio communications and electric power. Solar
activity is thought to have played a large role in the formation and evolution of
the solar system,
and strongly affects the structure of Earth's outer atmosphere.
Although it is the nearest star to Earth and has been intensively
studied by scientists, many questions about the Sun remain
unanswered, such as why its outer atmosphere has a temperature of
over a million K while
its visible surface (the photosphere) has a temperature of less than 6,000 K.
Current topics of scientific inquiry include the sun's regular
cycle of sunspot
activity, the physics and origin of solar flares and prominences, the
magnetic interaction between the chromosphere and the corona, and the origin of the solar wind.
About 74% of the Sun's mass is hydrogen, 25% is helium, and the rest is made up of trace quantities of
heavier elements. "G2" means that it has a surface temperature of
approximately 5,500 K, giving it a white color, which
because of atmospheric scattering appears yellow. This means that it generates
its energy by nuclear
fusion of hydrogen
nuclei into helium and is
in a state of hydrostatic balance, neither contracting nor expanding
over time. Because of logarithmic size distribution, the Sun is
actually brighter than 85% of the stars in the Galaxy, most of
which are red dwarfs.
The Sun orbits the center of the Milky Way galaxy at a distance of about 25,000 to 28,000 light-years from the galactic center,
completing one revolution in about 225?250 million years. The orbital speed is
217 km/s, equivalent to one light-year every 1,400 years, and
one AU every 8
The Sun is a third generation star, whose formation may have been
triggered by shockwaves from a nearby supernova. This is suggested by a high abundance of heavy elements such as
gold and uranium in the solar system;
these elements could most plausibly have been produced by endergonic nuclear reactions
during a supernova, or by transmutation via neutron absorption inside a massive second-generation
Sunlight is the main source of energy near the surface of Earth.
Sunlight on the surface of Earth is attenuated by the Earth's atmosphere so that less power
arrives at the surface—closer to 1,000 watts per directly
exposed square meter in clear conditions when the Sun is near the
zenith. This energy can
be harnessed via a variety of natural and synthetic
processes—photosynthesis by plants captures the energy of sunlight
and converts it to chemical form (oxygen and reduced carbon
compounds), while direct heating or electrical conversion by
solar cells are used
by solar power
equipment to generate electricity or to do other useful work. The energy
stored in petroleum
and other fossil
fuels was originally converted from sunlight by photosynthesis
in the distant past.
Sunlight has several interesting biological properties. Ultraviolet light from the
Sun has antiseptic
properties and can be used to sterilize tools. It also causes
sunburn, and has other
medical effects such as the production of Vitamin D. Its current age,
determined using computer models of stellar evolution and nucleocosmochronology, is thought to be about 4.57
The Sun does not have enough mass to explode as a supernova. The Sun is a
near-perfect sphere, with
estimated at about 9 millionths, which means that its polar
diameter differs from its equatorial diameter by only 10 km.
While the Sun does not rotate as a solid body (the rotational
period is 25 days at the equator and about 35 days at the poles), it takes approximately 28 days to complete
one full rotation; Tidal effects from the planets do not
significantly affect the shape of the Sun, although the Sun itself
orbits the center of
mass of the solar system, which is located nearly a solar
radius away from the center of the Sun mostly because of the large
mass of Jupiter.
The Sun does not have a definite boundary as rocky planets do; This
is simply the layer below which the gases are thick enough to be
opaque but above which
they are transparent; Most of the Sun's mass lies within about
0.7 radii of the
The solar interior is not directly observable, and the Sun itself
is opaque to electromagnetic radiation. However, just as seismology uses waves
generated by earthquakes to reveal the interior structure of the
Earth, the discipline of helioseismology makes use of pressure waves (infrasound) traversing the
Sun's interior to measure and visualize the Sun's inner structure.
Energy is produced by exothermic thermonuclear reactions (nuclear fusion) that
mainly convert hydrogen
into helium, helium into carbon, carbon into iron. All of the energy produced by fusion in the core
must travel through many successive layers to the solar photosphere
before it escapes into space as sunlight or kinetic energy of particles.
About 8.9 protons
(hydrogen nuclei) are converted into helium nuclei every second,
releasing energy at the matter-energy conversion rate of 4.26
million tonnes per second, 383 yottawatts (383 W) or 9.15 megatons of TNT per second. The rate of nuclear fusion depends
strongly on density, so the fusion rate in the core is in a
self-correcting equilibrium: a slightly higher rate of fusion would
cause the core to heat up more and expand slightly
against the weight of the
outer layers, reducing the fusion rate and correcting the perturbation; and a
slightly lower rate would cause the core to cool and shrink
slightly, increasing the fusion rate and again reverting it to its
The high-energy photons
(gamma and X-rays) released in fusion reactions take a long time to
reach the Sun's surface, slowed down by the indirect path taken, as
well as by constant absorption and reemission at lower energies in
the solar mantle. For many years measurements of the number of
neutrinos produced in the Sun were much lower than
theories predicted, a problem which was recently resolved
through a better understanding of the effects of neutrino
oscillation. while the material grows cooler as altitude
increases, this temperature gradient is slower than the adiabatic lapse
rate and hence cannot drive convection. Heat is transferred by
radiation—ions of hydrogen and helium emit
photons, which travel a
brief distance before being reabsorbed by other ions. Convective
overshoot is thought to occur at the base of the convection
zone, carrying turbulent downflows into the outer layers of the
The thermal columns in the convection zone form an imprint on the
surface of the Sun, in the form of the solar
granulation and supergranulation. Sunlight has approximately a black-body spectrum that
indicates its temperature is about 6,000 K (10,340°F / 5,727 °C), interspersed with
lines from the tenuous layers above the photosphere. The
photosphere has a particle density of about
1023 m−3 (this is about 1% of the
particle density of Earth's atmosphere at sea level).
During early studies of the optical spectrum of the photosphere, some
absorption lines were found that did not correspond to any chemical elements then
known on Earth. In 1868, Norman Lockyer hypothesized that these absorption lines
were because of a new element which he dubbed "helium", after the Greek Sun god
Helios. They can be
viewed with telescopes operating across the electromagnetic
spectrum, from radio through visible light to gamma rays, and comprise five principal zones: the
temperature minimum, the chromosphere, the transition
region, the corona,
and the heliosphere.
The heliosphere, which may be considered the tenuous outer
atmosphere of the Sun, extends outward past the orbit of Pluto to the heliopause, where it forms a
sharp shock front
boundary with the interstellar medium. The increase is because of a
transition as helium
within the region becomes fully ionized by the high temperatures. Rather, it forms a
kind of nimbus around
chromospheric features such as spicules and filaments, and is in constant, chaotic motion. The
transition region is not easily visible from Earth's surface, but
is readily observable from space by instruments sensitive to the far ultraviolet portion of
The corona is the extended outer atmosphere of the Sun, which is
much larger in volume than the Sun itself. The corona merges
smoothly with the solar
wind that fills the solar system and heliosphere. While no complete theory yet exists to
account for the temperature of the corona, at least some of its
heat is known to be from magnetic reconnection.
extends from approximately 20 solar radii (0.1 AU) to the
outer fringes of the solar system. Its inner boundary is defined as
the layer in which the flow of the solar wind becomes superalfvénic—that is,
where the flow becomes faster than the speed of Alfvén waves. The solar wind
travels outward continuously through the heliosphere, forming the
solar magnetic field into a spiral shape, until it impacts the heliopause more than 50 AU
from the Sun. In December 2004, the Voyager 1 probe passed
through a shock
front that is thought to be part of the heliopause. The
magnetic field gives rise to strong heating in the corona, forming
that are the source of intense solar flares and coronal mass ejections. The polarity of the
leading sunspot alternates every solar cycle, so that it will be a
north magnetic pole in one solar cycle and a south magnetic pole in
The solar cycle has a great influence on space weather, and seems
also to have a strong influence on the Earth's climate. During this
era, which is known as the Maunder minimum or Little Ice Age, Europe experienced very cold
temperatures. Earlier extended minima have been discovered through
analysis of tree rings
and also appear to have coincided with lower-than-average global
temperatures. The Van Allen belts consist of an inner belt composed
primarily of protons and
an outer belt composed mostly of electrons. The most energetic particles can 'leak out'
of the belts and strike the Earth's upper atmosphere, causing
auroras, known as aurorae borealis in the northern
hemisphere and aurorae australis in the southern hemisphere.
In periods of normal solar activity, aurorae can be seen in
oval-shaped regions centered on the magnetic poles and lying roughly at a geomagnetic
latitude of 65°, but at times of high solar activity the
auroral oval can expand greatly, moving towards the equator.
Theories proposed to resolve the problem either tried to reduce the
temperature of the Sun's interior to explain the lower neutrino
flux, or posited that electron neutrinos could oscillate, that is,
change into undetectable tau and muon neutrinos as they traveled between the Sun and the
Earth. Several neutrino observatories were built in the 1980s to
measure the solar neutrino flux as accurately as possible,
including the Sudbury Neutrino Observatory and Kamiokande.
Coronal heating problem
The optical surface of the Sun (the photosphere) is known to
have a temperature of approximately 6,000 K. The other is magnetic heating, in which magnetic energy is
continuously built up by photospheric motion and released through
reconnection in the form of large solar flares and myriad similar but smaller
Currently, it is unclear whether waves are an efficient heating
Faint young sun problem
Theoretical models of the sun's development suggest that 3.8 to 2.5
billion years ago, during the Archean period, the Sun was only about 75% as bright as
it is today. The general consensus among scientists is that the
young Earth's atmosphere contained much larger quantities of
(such as carbon
dioxide and/or ammonia) than are present today, which trapped enough
heat to compensate for the lesser amount of solar energy reaching
All matter in the Sun
is in the form of gas and
because of its high temperatures. The differential rotation of
the Sun's latitudes causes its magnetic field lines to become twisted together
over time, causing magnetic field loops to erupt from the Sun's
surface and trigger the formation of the Sun's dramatic sunspots and solar prominences (see
reconnection). This twisting action gives rise to the solar dynamo and an 11-year
solar cycle of
magnetic activity as the Sun's magnetic field reverses itself about
every 11 years.
The influence of the Sun's rotating magnetic
field on the plasma in the interplanetary
medium creates the heliospheric current sheet, which separates
regions with magnetic fields pointing in different directions.
Magnetohydrodynamic (MHD) theory predicts that the
motion of a conducting fluid (e.g., the interplanetary medium) in a
magnetic field, induces electric currents which in turn generates
magnetic fields, and in this respect it behaves like an MHD dynamo.
History of solar observation
Early understanding of the Sun
Humanity's most fundamental understanding of the Sun is as the
luminous disk in the heavens, whose presence above the horizon creates day and whose
absence causes night. In many prehistoric and ancient cultures, the
Sun was thought to be a solar deity or other supernatural phenomenon, and worship of the Sun was
central to civilizations such as the Inca of South America and the Aztecs of what is now Mexico. for example, stone megaliths accurately mark the summer solstice (some of
the most prominent megaliths are located in Nabta Playa, Egypt, and at Stonehenge in England); the pyramid of
Castillo at Chichén Itzá in Mexico is designed to cast shadows in
the shape of serpents climbing the pyramid at the vernal and autumn
equinoxes. With respect
to the fixed stars,
the Sun appears from Earth to revolve once a year along the
ecliptic through the
zodiac, and so the Sun
was considered by Greek astronomers to be one of the seven planets (Greek planetes,
"wanderer"), after which the seven days of the week are named in some
Development of modern scientific understanding
One of the first people in the Western world to offer a
scientific explanation for the sun was the Greek philosopher Anaxagoras, who reasoned that
it was a giant flaming ball of metal even larger than the Peloponnesus, and not the
chariot of Helios. For teaching this
heresy, he was imprisoned
by the authorities and sentenced to death (though later released through the
intervention of Pericles). In the early 17th century, Galileo pioneered telescopic observations of the
Sun, making some of the first known observations of sunspots and
positing that they were on the surface of the Sun rather than small
objects passing between the Earth and the Sun. Isaac Newton observed the
Sun's light using a prism,
and showed that it was made up of light of many colors, while in
Herschel discovered infrared radiation beyond the red part of the solar
spectrum. The 1800s saw spectroscopic studies of the Sun advance,
and Joseph von
Fraunhofer made the first observations of absorption lines in the
spectrum, the strongest of which are still often referred to as
In the early years of the modern scientific era, the source of the
Sun's energy was a significant puzzle. Lord Kelvin suggested that
the Sun was a gradually cooling liquid body that was radiating an
internal store of heat. Kelvin and Hermann von
Helmholtz then proposed the Kelvin-Helmholtz
mechanism to explain the energy output. Ernest Rutherford
suggested that the energy could be maintained by an internal source
of heat, and suggested radioactive decay as the source. However it would be
who would provide the essential clue to the source of a Sun's
energy with his mass-energy relation E=mc².
In 1920 Sir Arthur
Eddington proposed that the pressures and temperatures at the
core of the Sun could produce a nuclear fusion reaction that merged
hydrogen into helium, resulting in a production of energy from the
net change in mass. This theoretical concept was developed
in the 1930s by the astrophysicists Subrahmanyan
Chandrasekhar and Hans Bethe.
Solar space missions
The first satellites designed to observe the Sun were NASA's Pioneers 5, 6, 7, 8 and
9, which were launched between 1959 and 1968. Pioneer 9 operated
for a particularly long period of time, transmitting data until
In the 1970s, Helios
1 and the Skylab
Telescope Mount provided scientists with significant new data
on solar wind and the solar corona. The Helios 1 satellite was a
joint U.S.-German probe that studied the solar wind from an
orbit carrying the spacecraft inside Mercury's orbit at
Discoveries included the first observations of coronal mass
ejections, then called "coronal transients", and of coronal holes, now known to
be intimately associated with the solar wind.
In 1980, the Solar Maximum Mission was launched by NASA. This spacecraft was designed
to observe gamma rays,
X-rays and UV radiation from solar flares during a time
of high solar activity. In 1984 Space Shuttle Challenger mission STS-41C retrieved the satellite and
repaired its electronics before re-releasing it into orbit. The
Solar Maximum Mission subsequently acquired thousands of images of
the solar corona before re-entering the Earth's atmosphere in June 1989.
Japan's Yohkoh (Sunbeam)
satellite, launched in 1991, observed solar flares at X-ray
wavelengths. It was destroyed by atmospheric reentry in 2005.
One of the most important solar missions to date has been the
Solar and Heliospheric Observatory, jointly built by the
Agency and NASA and
launched on December
2, 1995. In addition to
its direct solar observation, SOHO has enabled the discovery of
large numbers of comets, mostly very tiny sungrazing comets which
incinerate as they pass the Sun.
All these satellites have observed the Sun from the plane of the
ecliptic, and so have only observed its equatorial regions in
detail. Once Ulysses was in its scheduled orbit, it began observing
the solar wind and magnetic field strength at high solar latitudes,
finding that the solar wind from high latitudes was moving at about
750 km/s (slower than expected), and that there were large
magnetic waves emerging from high latitudes which scattered
Elemental abundances in the photosphere are well known from
spectroscopic studies, but the composition of the
interior of the Sun is more poorly understood. A solar wind sample return
mission, Genesis, was designed to allow astronomers to directly
measure the composition of solar material. Genesis returned to
Earth in 2004 but was
damaged by a crash landing after its parachute failed to deploy on reentry into Earth's
exposure gradually yellows the lens of the eye over a period of
years and can cause cataracts, but those depend on general exposure to solar
UV, not on whether one looks directly at the Sun.
When looking at the sun, either with or without optical aid, using
a proper filter is important as some improvised filters pass UV or
IR rays that can damage the eye at high brightness levels. For
example, any kind of photographic color film transmits IR light and
must not be used.
Viewing the Sun through light-concentrating optics such as binoculars is very hazardous
without an attenuating (ND) filter to dim the sunlight. These
filters can be made of mirrored glass or metallised plastic
eclipses are hazardous to view because the eye's pupil is not adapted to the
unusually high visual contrast: the pupil dilates according to the
total amount of light in the field of view, not by the
brightest object in the field. This can damage or kill those cells,
resulting in small permanent blind spots for the viewer. The hazard
is insidious for inexperienced observers and for children, because
there is no perception of pain: it is not immediately obvious that
one's vision is being destroyed.
During sunrise and
sunset, sunlight is
attenuated through rayleigh and mie scattering of light by a particularly long passage
through Earth's atmosphere, and the direct Sun is sometimes faint
enough to be viewed directly without discomfort or safely with
binoculars (provided there is no risk of bright sunlight suddenly
appearing in a break between clouds).
- List of Solar System bodies formerly considered
- Formation and evolution of the solar
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