The Sun: Our Shinning Star

The Sun does not have a solid surface. Instead, its surface is a boiling, churring ocean of hot gases called the photosphere (meaning "light sphere") with a temperature of 6,000 kelvins (10, 340.6 degrees Fahrenheit). This region is the light-emitting portion of the Sun that we observe. The photosphere captured the imagination of many scholars from decade to decade, and thus was studied quite frequently. One tool, the McMath telecope, allowed scientists to do extensive research on the photosphere. This telescope produces an image of the photosphere 80 centimeters in diameter, the largest solar image produced by any existing telescope. The McMath telescope, along with other technological advances, and pure intellect, led to several discoveries about the sun, one of which being the phenomena called sunspots.

Sunspots gave the scientific community the first clues that the Sun was not a perfect, unvarying creation, but rather a place of constant change. Sunspots are defined as Earth-sized dark blemishes found on the surface of the sun. Although Chinese astronomers witnesses about 112 outbreaks of sunspots some 2000 years ago, Galileo Galilei became the first to study sunspots with a telescope in the early seventeenth century. Galileo used his telescope to project the sunspots onto a paper screen (thus he would not damage his eyes by looking directly at the sun), and by tracing their movement across the Sun's disk, formlated that the Sun rotates on an axis.

Through numerous studies pertaining to sunspots, scientists have noticed two main sections, the unbra and the penumbra. The umbra is the cooler, darker region of the sunspot, while penumbra is a outer, hotter region surrounding the unbra. The varying darknesses reflect a change in the temperature of the photosphere, thus, sunspots are actually coller areas of photospheric gas. The spots are composed of hot gases, with the temperature of the umbra averaging 4, 500 kelvins (7640.6 degrees Fahrenheit), the penumbra reaching about 5500 kelvins (9440.6 degrees Fahrenheit). They appear dark because they rest aganist the brighter, hotter background of the photosphere, reaching 5, 800 kelvins (9980.6 degrees Fahrenheit).

Sunspots come and go in cycles of about 11 years. At any given point in time the may ahve hundreds of sunspots, or none at all. When the spots are plentiful, the sun is said to be active, and when there are scarce, we call the Sun quiet. Despite the Sun's 92, 960, 000 miles from the Eartrh, the sunspots, like all the other regions of the Sun affect the climate here on Earth. American astronomer John A. Eddy reported that glaciers have come and gone in step with sunspots cycles for 7, 000 years. Eddy formulates that an active sun causes the glaciers to retreat and a quiet on causes then to advance. However, sunspots seem to affect solar activity as well.

The Sun's lower atmosphere is called the chromosphere (meaning "color sphere"), and when there are numerous sunspots, this region becomes especially active. The chromospere is just above the photosphere, and extends 2, 500 kilometers towards the sky. The dimeness of the chromosphere is a direct result of its low density. The chromosphere contains spicules (meaning "litlle spikes") which erupt to heights reaching 10, 000 kilometers. These long, flaming spikes of matter leave the surface of the Sun at about 10 kilometers per second (10 k/s), and the cover only about 1% of the Sun's entire area.

Flares are another type of solar activity discovered in the lower regions of the Sun's atmosphere. Flares pass across a region of the Sun in minutes at a time, and release exorbitant amounts of energy as they move. An active sun displays falres every hour or so, and because the amount of energy released is so great, the Sun's magnetic field is unable to bring the spewed particles back to its surface. Scientists have stated that one solar flare has the potential to release the energy of 10 million hydrogen bombs, reaching temperatures of 22 million kelvins.

Earlier we learned that the Sun's surface is not smooth. In fact, the photosphere appears grainy, as if it were covered with grains of salt or sand. This pattern is known as solar granulation. The individual grains are called granules, and though they appear small in a telescope, their typical size is about 1, 500 kilometers. The most impressive aspect of the granules is their dynamic motion, however since each granules lifespan is several minutes long, the human eye usually tires before observing the gradual changes.

The top layer of the Sun's atmosphere, the corona (meaning "crown") is perhaps the most marveled upon. The upper gases reach about 1,000,000 kelvins (1799540.6 degrees Fahrenheit), and they glow with a white light during a solar eclipse. Whe studied closely, the patterns of the spectral lines of the corona chagne dramatically, indicating either a change the corona's chemical make-up, a change in gas temperature, or both. Through both research and photographs of the corona scientists have discovered that the Sun, like planet Earth, has a north ans south magnetic pole, and therefore a magnetic field. Since the strength of the magnetic poles constantly change, the shape of the corona changes over a period of days or weeks.