The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma
interwoven with magnetic fields. It has a diameter of about 109 times that of Earth, and its mass accounts for about
99.86% of the total mass of the Solar System Chemically, about three quarters of the Sun's mass consists of
hydrogen, while the rest is mostly helium.
A full-disk multiwavelength extreme ultraviolet image of the sun taken by SDO on March 30, 2010. False colors trace different gas temperatures. Reds are relatively cool (about 60,000 Kelvin, or 107,540 F); blues and greens are hotter (greater than 1 million Kelvin, or 1,799,540 F). Courtesy of NASA/GSFC/AIA.
The Sun was formed about 4.57 billion years ago from the collapse of part of a giant molecular cloud that consisted
mostly of hydrogen and helium and which probably gave birth to many other stars. One or more supernovae must
have occurred near the location where the Sun formed. A shock wave from a nearby supernova would have
triggered the formation of the Sun by compressing the gases within the molecular cloud, and causing certain
regions to collapse under their own gravity. As one fragment of the cloud collapsed it also began to rotate due to
conservation of angular momentum and heat up with the increasing pressure. Much of the mass became
concentrated in the center, while the rest flattened out into a disk which would become the planets and other solar
system bodies. Gravity and pressure within the core of the cloud generated a lot of heat as it accreted more gas
from the surrounding disk, eventually triggering nuclear fusion. Thus, our Sun was born.
Three things cannot be long hidden: the moon, the sun, and the truth. Buddha.
Supernovae are a thing of beauty.
via upload.wikimedia.org Supernova remnant N 63A lies within a clumpy region of gas and dust in the Large Magellanic Cloud.
More after the jump.
The Sun's a yellow dwarf, because its visible radiation is most intense in the yellow-green portion of the spectrum and although its color is white, from the surface of the Earth it may appear yellow because of atmospheric scattering of blue light. It generates its energy by nuclear fusion of hydrogen nuclei into helium. In its core, the Sun fuses 620 million metric tons of hydrogen each second.
Once regarded by astronomers as a small and relatively insignificant star, the Sun is now thought to be brighter
than about 85% of the stars in the Milky Way galaxy, most of which are red dwarfs (the closest being a red dwarf
named Proxima Centauri at approximately 4.2 light-years away). The Sun is currently traveling through the Local
Interstellar Cloud in the Local Bubble zone, within the inner rim of the Orion Arm of the Milky Way galaxy. The Sun
orbits the center of the Milky Way at a distance of approximately 24,000–26,000 light-years from the galactic center,
completing one clockwise orbit, as viewed from the galactic north pole, in about 225–250 million years.
The atom bombs are piling up in the factories, the police are prowling through the cities, the lies are
streaming from the loudspeakers, but the earth is still going round the sun. George Orwell.
Our sun is very dynamic and it changes constantly. It has the largest eruptions in the solar system. These eruptions
can be so large that they can reach our planet and cause serious damage by disrupting satellites and other
communication devices. Our TV may not work, our cell phones will be down, a high speed train may run loose and if
an astronaut happens to be on the moon at the time when the sun erupts, he or she would be in great danger.
NASA uses satellites such as the Solar and Heliospheric Observatory (SOHO), to predict these eruptions so that
we have a warning of at least 2-3 days to protect our expensive communication devices during a solar eruption.
The sun is new each day. Heraclitus
Mysteries of the Sun: Solar variability (via MrAbkebab)
Sun Montage - SOHO NASA Solar Flare X-Flare Comet - PHJ - www.PHJ.ca (via TahitiPetey)
Big solar storm on January 23, 2012 seen by NASA's SOHO (via TheBadAstronomer)
The mean distance of the Sun from the Earth is approximately 149.6 million kilometers (1 AU), though the distance
varies as the Earth moves from perihelion in January to aphelion in July. At this average distance, light travels from
the Sun to Earth in about 8 minutes and 19 seconds. The energy of this sunlight supports almost all life on Earth by
photosynthesis, and drives Earth's climate and weather.
The English proper noun Sun developed from Old English sunne (around 725, attested in Beowulf), and may be
related to south. Cognates to English sun appear in other Germanic languages, all stem from Proto-Germanic
*sunnōn. The English weekday name Sunday is attested in Old English (Sunnandæg; "Sun's day", from before 700)
and is ultimately a result of a Germanic interpretation of Latin dies solis, itself a translation of the Greek heméra
helíou. The Latin name for the star, Sol, is widely known but is not common in general English language use; the
adjectival form is the related word solar.
Sunsets Around The World (via NoleeAimee)
People are like stained - glass windows. They sparkle and shine when the sun is out, but when the darkness
sets in, their true beauty is revealed only if there is a light from within. Elisabeth Kubler-Ross
Beautiful Sunrise and Sunsets (via CrnaLisica)
The insufferable arrogance of human beings to think that Nature was made solely for their benefit, as if it was
conceivable that the sun had been set afire merely to ripen men's apples and head their cabbages. Cyrano
Sunlight is Earth's primary source of energy. The solar constant is the amount of power that the Sun deposits per
unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1,368 W/m2 (watts per
square meter) at a distance of one astronomical unit (AU) from the Sun (that is, on or near 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
W/m2 in clear conditions when the Sun is near the zenith.
The use of solar energy has not been opened up because the oil industry does not own the sun. Ralph Nader
Solar energy can be harnessed by 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, sometimes employing concentrating solar power (that it is measured in suns). The energy
stored in petroleum and other fossil fuels was originally converted from sunlight by photosynthesis in the distant
Mortimer´s vision of the Sun,
Like other natural phenomena, the Sun has been an object of veneration in many cultures throughout human
history. In many prehistoric and ancient cultures, the Sun was thought to be a solar deity or other supernatural
phenomenon. Worship of the Sun was central to civilizations such as the Inca of South America and the Aztecs of
what is now Mexico.
Mayan Calendar vs Aztec Sun Stone & December 21, 2012 (via PiPhD)
Many ancient monuments were constructed with solar phenomena in mind; for example, stone megaliths
accurately mark the summer or winter solstice (some of the most prominent megaliths are located in Nabta Playa,
Egypt; Mnajdra, Malta and at Stonehenge, England); Newgrange, a prehistoric human-built mount in Ireland, was
designed to detect the winter solstice; the pyramid of El 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.
Snake of light seen on the Great Pyramid of Kukulkan in Chichen Itza at autumn equinox, via farm1.static.flickr.com
If I had to choose a religion, the sun as the universal giver of life would be my god. Napoleon Bonaparte
In the late Roman Empire the Sun's birthday was a holiday celebrated as Sol Invictus (literally "unconquered sun")
soon after the winter solstice which may have been an antecedent to Christmas.
How the Sun could get a scientist in trouble:
Greek philosopher Anaxagoras, who reasoned that it was a giant flaming ball of metal even larger than the
Peloponnesus rather than the chariot of Helios, and that the Moon reflected the light of the Sun. For teaching this
heresy, he was imprisoned by the authorities and sentenced to death. He was lucky Pericles was there and saved
him. Therefore, Galileo Galilei was not the first one to be in this kind of trouble, and the Inquisition was not invented
in Spain, where nobody expected it.
The first satellite designed to observe the Sun was NASA's Pioneer 5 , launched in 1959.
Sunsibility and health:
Skin cancer is caused primarily by exposure to ultraviolet (UV) radiation – either from the sun or from artificial
sources such as sunbeds. Excessive sun exposure in children and adolescents is likely to contribute to skin
cancer in later life.
Worldwide approximately 18 million people are blind as a result of cataracts, of these 5% of all cataract related
disease burden is directly attributable to UV radiation exposure.
- Rob: Max, if we lived in California, we could play outdoors every day, in the sun.
- Alvy Singer: Sun is bad for you. Everything our parents said was good is bad. Sun, milk, red meat, college.
(Annie Hall script by Woody Allen)
There are also important health benefits attributed to a small daily dose of sunlight, including: boosts our mood,
improves sleep, promotes vitamin D production, protection from autoimmune diseases and lessening of
This must my comfort be:
That sun that warms you here shall shine on me. (William Shakespeare )
Ultraviolet light from the Sun has antiseptic properties and can be used to sanitize tools and water.
Ultraviolet light is strongly attenuated by Earth's ozone layer, so that the amount of UV varies greatly with latitude and
has been partially responsible for many biological adaptations, including variations in human skin color in different
regions of the globe.
How the Sun can destroy you vision:
Looking directly at the Sun causes phosphene visual artifacts and temporary partial blindness. It also delivers
about 4 milliwatts of sunlight to the retina, slightly heating it and potentially causing damage in eyes that cannot
respond properly to the brightness. UV exposure gradually yellows the lens of the eye over a period of years and is
thought to contribute to the formation of cataracts, but this depends on general exposure to solar UV, not on whether
one looks directly at the Sun. Long-duration viewing of the direct Sun with the naked eye can begin to cause UV-
induced, sunburn-like lesions on the retina after about 100 seconds, particularly under conditions where the UV
light from the Sun is intense and well focused;[ conditions are worsened by young eyes or new lens implants
(which admit more UV than aging natural eyes), Sun angles near the zenith, and observing locations at high
Partial solar 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. During partial eclipses most sunlight is blocked by the Moon passing in front of the Sun, but the uncovered
parts of the photosphere have the same surface brightness as during a normal day. In the overall gloom, the pupil
expands from ~2 mm to ~6 mm, and each retinal cell exposed to the solar image receives about ten times more
light than it would looking at the non-eclipsed Sun. 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.
Neither the sun nor death can be looked at with a steady eye. Francois de La Rochefoucauld
The Solar Eclipse In Varanasi - Wonders of the Solar System - Series 1 Episode 1 Preview - BBC Two (via BBC)
How the Sun made a Nobel Prize:
Hans Bethe received the 1967 Nobel Prize in Physics for revealing how the Sun behaves like a giant nuclear reactor
to produce the vast amount of heat and light that supports life on Earth. Bethe's breakthrough work stems from the
British astronomer Sir Arthur Eddington's hypothesis in the 1920s that the intense temperatures and pressures
within the Sun can force the nuclei of atoms to fuse and create heavier atoms, releasing a tremendous amount of
energy in the process. In two papers in 1938 and 1939 Bethe described the two nuclear reactions that stars use to
produce energy, and showed how one predominates over the other depending on the internal conditions. For stars
up to and including the size of the Sun, the more dominant energy supply is generated by squeezing four hydrogen
nuclei together to form one helium nucleus. In the more extreme temperatures and pressures found in stars that
are heavier than our Sun, the dominant energy supply also transforms hydrogen into helium, but this involves a
more complex cycle of nuclear reactions in which carbon acts as a catalyst. Albert Einstein's most famous equation,
E=mc2, showing that mass and energy are interchangeable, explains why these fusion reactions create heat and
light. The mass of helium is less than the sum of the hydrogen nuclei, and the difference in mass is converted into
large quantities of energy.
Concentrate all your thoughts upon the work at hand. The sun's rays do not burn until brought to a focus.
Alexander Graham Bell.
How the Sun Makes the Wind Blow:
The part of the Earth near the equator receives more of the sun’s energy than the North and South Poles. Some
parts of the Earth receive and/or absorb more solar energy than others. Some parts reflect more of the sun’s rays
back into the air. Light-colored surfaces and water reflect more sunlight than dark surfaces. Snow and ice reflect
sunlight, too. Some types of land absorb more solar energy than others. Dark forests absorb sunlight, while light
desert sands reflect it. When the Earth’s surface absorbs the sun’s energy, it turns the light into heat. This heat on
the Earth’s surface warms the air above it. The air over the equator gets warmer than the surface air near the poles.
The air over the desert gets warmer than the air in the mountains. The air over the land usually gets warmer than
the air over the water. As air warms, it expands. The warm air over the land becomes less dense than the cooler air
and rises into the atmosphere. Cooler, denser air nearby flows in to take its place. This moving air is what we call
wind. It is caused by the uneven heating of the Earth’s surface.
Sunflower (Helianthus annuus) is an annual plant native to the Americas. What is usually called the "flower" on a
mature sunflower is actually a "flower head" (also known as a "composite flower") of numerous florets (small
flowers) crowded together. The outer petal-bearing florets are the sterile florets and can be yellow, red, orange, or
other colors. The florets inside the circular head are called disc florets, which mature into seeds.
Some painters transform the sun into a yellow spot, others transform a yellow spot into the sun. Pablo
Every friend is to the other a sun, and a sunflower also. He attracts and follows. Jean Paul
Bob marley sunshine reggae (via supersleepyme)
Here Comes The Sun (via JimiHendrixANDVADER)
You've got the sun, you've got the moon, and you've got the Rolling Stones. Keith Richards´ sort of a brain.
Animals - House Of The Rising Sun (via logiax)
bob marley i can see clearly (via 3900blok)
Elton John - Dont let the sun go down on me live (via greensman49)
Cream - Sunshine of your Love (via SmellsLikeReason)
Sunshine Trailer (via giagirl)
Now we can go back to the Olympics.