The God of Life.
The Sun God, worshiped by most primitive civilizations. At noon it is the bright hot disk in the sky. We can feel heat from the Sun. We can see the Sun. We can be burnt or blinded if we stay out unprotected in the Sun's rays. Without the Sun, we would die.
The Sun generates an enormous quantity of energy regularly and ceaselessly. One of the most important characteristics of the Sun is its constant radiation of energy. Approximate output is 4 x 10^26 joules or 9.6 x 10^25 calories per second meter squared.
The Sun's surface temperature is about 5,750 degrees Kelvin and internal temperatures can be as hot as 850,000 degrees Kelvin.
The Suns diameter is 1.39 million kilometers, 864,000 miles or 110 times the diameter of the Earth.
The mass of the Sun is approximately 1.78 x 10^33 grams or 330,000 times that of the Earth.
There are three terms which describe the general make-up of the Sun. The core, photosphere and corona. The core of the Sun is where the nuclear reaction occurs. The photosphere is the outer layer of the Sun which is the center of the disk. The corona is plasma gasses extending away from the edges of the photosphere. The corona's intensity and density decrease rapidly as distance from the photosphere increases, however, the Earth is sill within the corona.
The Sun is traveling through space toward Vega and makes one revolution around the center of the galaxy every 200 million years.
The Sun is believed to be deriving its energy from the fusion of elements. The basic elements which are believed to be in this reaction are the lighter ones primarily hydrogen and helium. This action is that of a hydrogen bomb and can easily account for massive amounts of energy which the Sun radiates for astronomical lengths of time. Accounting for the energy by combustion the Sun would have died billions of years ago. It is believed that the Sun burns approximately 564 million tons of hydrogen into 560 million tons of helium per second. 4 Million tons of mass is liberated at E = MC^2 per second.
Looking at the Sun's coronal surface with special telescopes and filtering out all but spectral lines of light which correspond to the fusion of elements, it shows the surface to be nodular. The nodule wave pattern can be reproduced by a high-school water wave tank or one can view a similar pattern on the bottom of a swimming pool. The nodes are typically seen when a random wave pattern is reflected off the sides of a water tank or generated by several independently random sources.
Sun spots and coronal holes appear regularly on the Sun's surface. Sun spots are believed to be massive magnetic disturbances which cause severe temperature losses on the Sun's photosphere. Sun spots normally occur in groups between 5 and 40 degrees north or south latitude. Sun spots range in size from 100 kilometers to more than 100,000 kilometers in diameter. The magnetic intensity of the Sun spots is in the range of 600 to 6000 gauss. Sun spots group density and magnetic polarity reversals indicate that there is a 22.5 year cycle associated with Sun spots. A spot's existence is generally on the order of 4 days but has been as long as a year and a half. Skylab experiments has shown that coronal holes are real three dimensional objects in the Sun's photosphere.
Generally speaking the Sun rotates about its axis every 27 days. However, the center of the Sun rotates faster than the polar areas. Thus, it is hard to give a rotational time period, but generally is 24 days at the equator and 34 days at the poles. This indicates that the surface of the Sun is not a solid. The inclination of axis of rotation to the Earth's orbit is about 7 degrees and wobbles or cycles in less than a year. The rotational period has been derived by two methods; one is by radial velocity measurements of the solar limb and the application of the doppler principle, and the other method is to measure the sunspots drift around the Sun.
Prominences or coronal streamers are material blown away from the Sun. The distance these disturbances can be seen extends millions of miles into space. On occasions the streamers can brush the Earth and produce magnetic storms and auroral displays. The velocity of these particles can exceed 350 kilometers per second or about 800,000 miles per hour. These occurrences are not predictable, however, they do occur regularly.
A more consistent departure of material from the Sun is the Solar Wind. The Solar Wind consist of ionized gas, or plasma particles moving away from the Sun. The density of the particles is about 2 to 20 particles per cubic centimeter. Hydrogen protons are the predominant ion making up 80 percent of the particles and helium making up the other 20 percent. Bulk speed of the particles is about 400 kilometers per second or about 900,000 miles per hours, and speeds doubling these figures have been recorded. The electron potential of the wind is about 5000 electron volts, but figures of 100,000,000 electron volts have been measured. The solar wind is a very good conductor of a wave and electromagnetic energy.
It is considered that the particles are moving away from the Sun along open magnetic lines from the Sun, because plasma motion generally follows magnetic field lines. Thus, tending to align matter in the solar atmosphere which coincides with the magnetic field. The far magnetic field lines are nearly parallel to the solar equatorial plane and have an Archimedean spiral shape.
Distance from the Sun.
Boundary of the magnetic field showing a current sheet separating the magnetic field polarity. L. G. Burlaga
General Structure of Interplanetary Magnetic Field. J. Lemaire
Showing an equatorial Archimedean spiral of a magnetic field (+) away from and (-) towards the Sun. This is a surface/time affect caused by the Suns magnetic field at the surface of the Sun. Each wave arm seems to be opposite in polarity between one spiral and the next. Several questions pop up regarding this magnetic affect, are the spirals moving, does the number of arms change, and is there sub intensities? The answers to these questions are yes and on occasions. This affect is very important. This effect has not been measured very much. If the magnetic vectors changed direction, one would think the current sheets would change direction but that does not seem to be the case.
Studying the over all magnetic structure of the Sun is difficult because of not being able to send a device close enough to the Sun to measure it and its astronomical size. However, there are several ways of looking at the Sun's surface magnetic fields. One way is using the Zeeman effect. The problem with all the measuring techniques is that one can see the trees but can not see the forest. Results from these observations of the polar magnetic fields made in 1968 with the Mount Wilson magnetograph show the south polarity near the heliographic north and visa-versa. Babcock in the spring of 1957 observed the fields seemed to be of the same sign for both poles. This lasted for about one and half years. Thus, it is believed that the near magnetic poles of the Sun reverse every 22 years, with some time which both poles are the same polarity. But far field magnetic measurements seem to indicate a more stable condition and reversal is not present. Basically, this is a case of what to believe; the near field effects measurements or the far field measurements or both or what?
Very close to the Sun's surface shows the magnetic structure to be similar to that of the Earth's atmospheric wind cells. Meaning that within the solar disk magnetic north can be opposite to that of a cell above and below. Thus, near to the Sun's surface the magnetic polarity has no resemblance to a dipole magnetic. Most very near magnetic measurements, when taken over a time period, show a very unstable arrangement. Magnetic flux fields are a jumbled mess as drawn to the right.
As the distance from the Sun increases, a more stable magnetic emerges. The field is similar to a dipole, however, at the equatorial region the field seems to expand outward. Thus, the dipole geometry does not apply. The interplanetary magnetic field is effected by Solar flares. The interplanetary magnetic field perturbation can be as far out to be beyond the solar system as shown by Kenneth Schatten below.
There are many classes of stars. The Sun is Earth's star. The Sun is typically the same as the rest of the stars.
Stars have the principal classifications groups labeled as O, B, A, F, G, K, and M. Special cases are S, R, N, and W stars. Each group has 10 subgroups. The classifications are based primarily on temperature range of the stars luminosity. The Sun belongs to the class G2.
G class stars typically are 5000K to 6000K. The spectral lines of neutral metals become strong, whereas the hydrogen lines continue to weaken. Lines of ionized calcium are very strong. Molecular bands of CN and CH appear. (Note: as the understanding of the stars increases, this classification will fail because stars are too complex to group this way.)
Further definitions of star groups have appeared as: Red giants, subgiants, white dwarfs, and blue giants. As time goes on the definitions increased to galactic clusters, strong-line stars, weak-line stars, high-velocity stars, bright red giants, globular clusters and sub dwarfs. These definitions are based around the luminosity of the star regarding its power output and spectral lines, its mass, its radius, its absolute bolometric magnitude, and outward mass migration.
It seems that one of the basic characteristics of a star is its age. To this there is the term sequence of stellar population. The Sun is said to be in its main sequence.
The Sun and Earth have a similar characteristic. The solar space around the Earth is hotter than the surface of the Earth and the Earth's interior is hotter than the surface. The same seems to be true with the Sun. The gasses above the surface of the Sun seem to be hotter than those at the surface and the Sun's interior gasses are hotter than the surface.
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