The Suns diameter is864,938 miles (1,391,980km). This is almost 10times larger than theplanet Jupiter and about109 times as big as theEarth. The volume of theSun is 1,299,400 timesbigger than the volumeof the Earth; about1,300,000 Earths could fitinside the Sun
STUDYING THE SUNAstronomers study the Sun using special instruments.Scientists analyze how and why the amount of lightfrom the Sun varies over time, the effect of the Sunslight on the Earths climate.
We have always built bridges to the sky. Our earliest ancestors were skywatchers, making careful observations of the Sun and Moon, making drawings and paintings and keeping count of changes on sticks and tablets. By the 17th century, new tools were being used to reach the sky -- telescopes were invented and discovered new worlds and a new Universe. Great Balls of Fire -- NOT! Astronomers studying the Sun discovered that it is composed of gases, not fire, and first discovered the gas helium in the Suns spectrum. Many civilizations observed the rising and setting positions of the Sun as a celestial marker -- a calendar. These changing positions could be used to prepare for annual floods, times for planting and harvesting and migrating to avoid inclement temperatures.
Telescope designs improved, and larger telescopes were built, along with special buildings to house them -- observatories. By the 20th century, astronomers built telescopes to study wavelengths other than visible light, beginning with radio telescopes. Today, modern tools study the light -- and the reflected light -- we see from the Sun, Moon, planets, comets, and stars. We use radio telescopes to study radio waves, space-borne gamma ray telescopes to observe gamma rays, and other telescopes to study everything in-between. Ancient peoples did not all rely solely on the Sun; many also kept track of the changing Moon -- leading to our use of the month. The appearance of certain stars in the sky were also used as a clock and calendar;
Sunspots are relatively cool, darkpatches on the suns surface.They come in many shapes andsizes; they often appear ingroups. These spots are muchbigger than the Earth; they canbe over 10 times the diameter ofthe Earths.Individual sunspots only last forone to two weeks, but thenumber of sunspots follows an 11year cycle. The current sunspotcycle will peak in the middle of2000. Sunspots are visible fromEarth.The sunspot cycle was discoveredby S. Heinrich Schwabe in 1843(he started his observations in1826).
SOLAR GRANULES: Granulation is solar granules together with intergranular lanes (dark, cool areas between granules where solar material is descending into the surface). Granulation covers the visible surface (the photosphere) of the Sun. GRANULES: Granules are regions of the sun where hot solar material comes to the solar surface. Granules are about 600 miles (1,000 km) across and only exist for about 5 to 10 minutes before they fade away. It is almost as though the surface of the Sun is bubbling like a pot of boiling water.
Solar faculaeA facula (plural: faculae) is literally a "brightspot." It is used in planetary nomenclature fornaming certain surface features of planets andmoons, and is also a type of surfacephenomenon on the Sun.Solar faculae are bright spots that form in thecanyons between solar granules, short-livedconvection cells several thousand kilometersacross that constantly form and dissipate overtimescales of several minutes. Faculae areproduced by concentrations of magnetic fieldlines.
A plage is a bright region in the chromosphere of the Sun, typically found in regions of the chromosphere near sunspots. The term itself is poetically taken from the French word for "beach
SOLAR FLARESa magnetic storm on the Sun which appears to be a very bright spot and a gaseous surface eruption.they are ejected thousands of miles from the surface of the Sun.were first observed by in 1859 by Lord Richard C. Carrington. He wrote that as he was watching the sun with a telescope, he saw "two patches of intensely bright and white light" near a huge group of sunspots. Just a few seconds later, the flare has disappeared.
A solar prominence (also known as a filament) is an arc of gas that erupts from the surface of the Sun. Prominences can loop hundreds of thousands of miles into space. Prominences are held above the Suns surface by strong magnetic fields and can last for many months. At some time in their existence, most prominences will erupt, spewing enormous amounts of solar material into space.
Solar prominence are sheets of luminous gas emanating from thesun’s surface – they would appear dark against the sun’s disk butbright against the dark sky and occur in regions of horizontalmagnetic fields. Here is a NASA photo of a solar prominence.
The solar wind is a continuous stream of ions (electrically charged particles) that are given off by magnetic anomalies on the Sun. The solar wind is emitted where the Suns magnetic field loops out into space instead of looping back into the Sun. These magnetic anomalies in the Suns corona are called coronal holes. In X-ray photographs of the Sun, coronal holes are black areas. Coronal holes can last for months or years.