Ancient Civilizations & The Sun

The Greeks referred to the Sun as “Helios,” whereas to the Romans, it was known as “Sol.” Many other ancient civilizations such as the Incas of South America treated the Sun as a god and worshipped it. While the god of the Sun to the early Egyptians was called “Ra.” They believed “Ra” was born every morning, and traveled across the sky.

Other than Sun worship, numerous ancient civilizations built monuments to interact with the Sun. An example of this is the megaliths of Egypt, and the E. Castillo pyramid of Mexico. This pyramid has 365 steps for each day in a year.

The Early Greeks thought the Sun revolved around the Earth and considered it a planet. However, sixteenth century Copernicus is thought to be the first European to form the theory of the Sun being in the center, with the planets moving around it. 

Expeditions To The Sun

The first American expedition to the Sun was spearheaded by NASA, using the Pioneer 5 satellite. The Pioneer 5 satellite was launched in 1959 into the Earth’s atmosphere, and took measurements of the Sun’s diameter and solar wind, while observing the surface activity of this great star. The last Pioneer satellite, Pioneer 9, was launched in 1968, and transferred information about the Sun until the 1980s.

A second solar mission involved the satellite Helios 1, launched in 1974, and a joint effort between the United States and Germany. Helios 1 was sent to orbit near Mercury, with the second satellite, Helios 2 launched in 1975.

The largest mission to investigate the Sun was using the Solar and Heliospheric Observatory (SOHO) spacecraft. This spacecraft left the Earth in 1995, as a joint effort between the United States and the European Space Agency. The SOHO spacecraft is still operating, and continually provides some of the best images ever taken of the Sun.

It should be stated only the major solar missions have been discussed above, but there were other minor solar missions completed between 1959 to the present.

The Sun’s Composition

The Sun is a yellow G2 star located at the center of the solar system, and even though it is the largest structure in our solar system, it is one of many million stars. Scientists believe the Sun is approximately 4.6 billion years old (middle-aged). It is composed of gases such as Hydrogen (70%), Helium (28%), and Trace Elements (2%). The Sun has a circumference of 2,715,000 miles, which is 109 times the circumference of Earth. It has nine planets revolving around it, along with asteroids and comets.

Surrounding the Sun is the solar atmosphere consisting of the heliosphere, corona, chromosphere, and transition region.

The heliosphere or magnetosphere is the magnetic field of the Sun. It contains the stream of charged particles known as solar wind. It has been discovered this magnetic field extends past Pluto to the outer regions of the Solar System.

The outer boundary of the solar atmosphere surrounding the Sun is the Corona. The temperature of the corona is measured in megakelvins, and it is hotter than the 1 million Kelvin of the transition region. Located within the corona are structures called “prominences.” The prominences are puffs of gas, which burst forth from the chromosphere. The corona is also visible during a total solar eclipse.

Just below the corona lies an area known as the chromosphere. It is approximately 1,240 miles in length, and is the site of emissions and absorption. The chromosphere is seen as a visible color before the eclipses of the Sun. The temperature at the boundary of the chromosphere can reach up to 100,000 K.

The lower level of the Sun’s atmosphere is called the photosphere. It has a temperature of 5800 K, and the layer we see when looking at the Sun. This layer of the Sun is quite opaque to light, resulting from a decrease in hydrogen ions that are responsible for absorbing light. In the photosphere are structures known as sunspots. It is not entirely sure how sunspots develop, but it is believed an interaction with the magnetic field of the Sun produces these cooler areas. The temperature of a sunspot is only 3800 K, and they can be as wide as 31,000 miles.

As we continue towards the center of the Sun, the next layer after the photosphere is the convection layer. In the convection layer, photons of life will travel through this area to reach the photosphere and outer surface of the Sun.

Below the convection layer and closer to the core of the Sun is the radiation layer. This layer will emit radiation in the form of photons, which have been produced in the core.

The core of the sun is responsible for producing heat in the process called nuclear fusion. The pressure of the core is at least 340 billion times greater than the pressure on Earth.  The temperature of the core reaches approximately 27,000,000 degrees Fahrenheit (15,000,000 degrees Celsius), and is the hottest part of the Sun.

How Does The Sun Produce Light

The Sun is able to produce light using nuclear fusion in its core. Its high temperature and pressure in its create the perfect environment in its core to convert hydrogen into helium. As a result of this process, heat energy is released. This reaction also releases photons in the form of gamma rays and X-rays.

Each gamma ray will produce millions of photons within the Sun, and be released into space. The Sun is able to transform 700 million tons of hydrogen into helium every second, resulting in 5 million tons of energy being produced every second.

The Sun is very slowly reducing in composition, and becoming less heavy. Like other stars exactly like it, it will burn out as it runs out of hydrogen in its core. The lost of hydrogen will cause the core to collapse, and the subsequent combination of helium with other elements such as carbon. This will lead to swelling in the core of the Sun into a Red Giant, which will consume the Earth with its intense heat.

Statistics About The Sun

References

National Aeronautics and Space Administration (N.A.S.A). “Sun: Facts & Figures.” 2006.
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sun&
Display=Facts

World Book, Inc. "Sun." World Book Online Reference Center. 2006. World Book, Inc.
http://www.worldbook.com/wb/Article?id=ar539440&st=the+sun

Sun Images