THE SUN

The Sun: Sol  

 

The Sun is the life-giver. Without it, there would be no life on earth because plants utilized the sun's energy and animals need plants to survive. Less than half a billionth of the Sun's output of enery actually reaches the earth, but it is enough to power the entire globe. The Sun is by far the largest object in our solar system, making up 99.8 percent of the mass in the solar system. What little is left is mostly Jupiter's mass. A million earth's could easily fit into the sun, with room to spare. Before mankind was able to comprehend the earth's dependency on the Sun, many ancient cultures- Egyptians, Greeks and Romans- considered the bright ball as a God that brought light. Now we are beginning to appreciate the sun's complexity and magnificence.

General Information about the Sun:

• Diameter (miles)= 865,000
• Volume= 1,300,000 times that of earth
• Temperature= Surface =10,000 degrees Farenheit Center 27,000,000 degrees Farenheit
• Age=4,600,000,000
• Rotation period=1 month
• Revolution around Milky Way= 200 million years

Detailed Information on the Sun:

Sun's Compostion and Mass--

Nearly three-fourths of the mass of the sun is hydrogen, the lightest of the known elements. The other fourth is pretty much helium ( the word "helium" comes from the Greek word "Helios", meaning sun.) Since the sun is so large, the force of gravity extered is far greater than that of any of our planets. Thus, objects would weigh more on the sun than on any planet. For example, a boy who weighs 100lbs on earth would weigh about 2,800lbs on the sun. It is through the force of gravity that the sun controls the orbit of the planets in the solar system. In addition to the planets, the sun also pulls its own gases toward the center. These gases are extremely hot and thus have expansive tendencies which serve to counteract the sun's gravity, preventing collapse.

How the sun was born and how old it'll get--

Within our galaxy, the Milky Way, and even between galaxies, there are huge clouds of gas and dust. When portions of these gas clusters begin to condense under the force of gravity, stars are born. Eventually, thermonuclear reactions take place which produce energy and cause the masses of gas and dust to shine as a star. It is believed that our sun was formed in this manner. Although details of the solar system's birth are not known, study and exploration are helping scientists to understand. Enough energy is released from thermonuclear reactions that the sun will probably shine for ten billion years. So, since the sun is about 4,600,000,000 years old it will shine for at least 5,000,000,000 more years. After that time passes the sun will shrink and become hotter on the inside, though slightly coller on the surface. The outer regions of the sun will expand, probably encompassing Mercury at which point it will be a red giant. After all its thermonuclear energy has been used, it will begin to shrink until it becomes a white dwarf . The sun may then throw of gases in violent eruptions called nove explosions during its change to a white dwarf. After billions of years as a white dwarf it will have used up all energy and heat. Such stars are known as black dwarfs .

The Sun's interior and surface--

At the center of the sun, the core , the material is more than 100 times the density of water, but still consists of gases. It is in this region where thermonuclear reactions occur. Just beyond the core is the radiative zone which extends through the middle of the sun's interior. The temperature in this zone is about 4,500,000 degrees Farenheit. since heat tends to flow from hot to cool places, this drop in temperature causes the energy to flow towards the surface. The convection zone , just below the surface, extends a few hundred miles below until it meets the radiative zone. In the convection zone the temperature is about 2,000,000 degrees Farenheit and the gases are about a tenth as dense as water. The actual name for the sun's surface is the photosphere . It is 200 miles thick and maintains a temperature of about 10,000 degrees Farenheit. The photosphere contains a number of small patches of gas called granules . A typical granule lasts only 5 to 10 minutes and then fades away. Other features of the photosphere are studied in order to learn more about the sun. Among these features are sun spots (see Stormy Activity below).

Sun's Atmosphere--

At about 100 miles above the photosphere the chromosphere begins. This is the middle region of the sun's atmosphere and has a temperature of about 50,000 degrees Farenheit. Part of it consists of streams of gas that shoot up briefly, called spicules . Each spicules lasts up to 15 minutes and can be 500 miles thick. Just above the chromosphere is the corona where the temperature varies from 2,000,000 to 3,000,000 degrees Farenheit. However, the molecules of the corona are so far apart that the gasses present in this region have little heat, only the direct rays of the sun give the corona its temperature.

The Sun's Stormy Activity--

A variety of spectactular activities take place on the sun. Here is a general overview of each: Solar Magnetism -The reason that various stormy activities occur is because of the changes in the magnetic field of the sun. A magnetic field is the area around a magnet where magnetism exerts a force. The sun's magnetic fields somewhat resembles that of a bar magnet, especially near the sun's poles. However, near the center, the magnetic field is irregular because of the movement of gases. The atoms of these gases are ionized and those atoms that have lost electrons for a gas called plasma . The motion of large quantities of plasm distort the magnetic lines of force by changing their direction. As a result, changes occur in the magnetic field, and cause stormy activity.
Prominences - Promences are bright arches of gases that outline lines of magnetic force. These arches shine brightly because the gases are of less density and radiate light more efficiently than the gases in the chromosphere and corona. Typical prominences may reach up to 20,000 miles above the sun's surface and be about 3,000 miles thick. There are two classes of prominences- quiescent and active. During its two or three month existence, a quiescent prominence changes very little. On the other hand, an active prominence changes quite rapidly over a period of only several hours.
Sunspots - When strong loops of magnetic lines of force extend through the sun's surface, they lower the temperature of the gas. Thus, the gas does not shine as brightly as the surrounding gas and appears as a sunspot. Soon, the magnetic loop may break up into thinner loops resulting in a sunspot group . The typical sunspot diameter is 20,000 miles. A sunspot has two parts: the umbra and penumbra . The penumbra is the outer part which is hotter and therefore brighter.
Flares - If a sunspot group (see above) has existed for a long time, the magnetic lines of force will usually become jumbled. The energy may be released in a discharge known as a solar flare . The energy is released in the form of light, heat and cosmic rays. Flares may be as small as a sunspot or as large as a sunspot group. A small flare may last only ten minutes while larges flares reach about an hour.
Solar Wind - Since the corona is extremely hot, gases in this area slowly expand away from the sun. This flow of gases will eventually mix with gases near the outer planets of the solar system. It is this flow of gases that is called the solar wind. It generally travels from 1 to 2 million miles per hour.