The Sun, at Center of our Solar System

The sun is just one of the billions of stars that exist in the galaxy. However, it is the star closest to the earth and is also at the center of the solar system. It is a large ball of incandescent plasma and its core is its hottest matter at 27 million° Fahrenheit. It takes about 8 minutes for the sun’s light to reach the earth. The sun does not rise or set.  It only appears to do so because the earth is moving.

The Sun
The Sun, a burning call of fire.  Image credit SDAC.

The Sun Is the Largest Component of the Solar System

The sun is the largest component of the solar system. It accounts for more than 99.86% of the mass of the entire solar system.  The eight planets and other smaller bodies orbiting around the sun account for just a fraction of the solar system. These are sun’s satellites.

While it is not the biggest star in the galaxy, the sun’s diameter is 109 times that of the earth. This means that more than a million earths could fit inside the sun.  The sun has a near perfect sphere. The diameter at the equator and the diameter at the poles only differ by 10km.

The Ancient Communities Were Fascinated By the Sun

For years, people tried to understand and explain the sun leading to folklores. Ancient civilizations believed the sun to be a burning ball of fire created by the gods. Later, people believed it was a solid or liquid ball.

Some communities such as the Romans worshipped the sun because they recognized that it brought life. The Romans nicknamed it Sol and the Greeks called it Helios.

Without The Sun, There Would Be No Life on Earth

The sun supplies the earth with the energy required for life to thrive. It emits heat and light and is responsible for the favorable climate and weather that makes Earth the only known planet to support life.

The Sun is a Middle Aged Star

Scientists believe that the sun and the other planets formed about 4.59 million years ago from the solar nebula. According to them, the sun is only at the middle of its life, which is the main sequence stage and it has already used half of its hydrogen fuel. In the next 5-7 billion years, the sun will move into the red giant phase after consuming all of its hydrogen.

What Is The Sun Made Up Of?

The sun is mainly composed of hydrogen and helium but also contains traces of iron, nickel, oxygen and other elements in the solar system. Even though it appears to be a burning ball of fire, it has an internal structure. The visible area is known as the photosphere and then there is the convective zone, the radiative zone where heats travels through radiation and the core where molecules of hydrogen fuse into helium and release energy.

The Sun Has Sunspots

Sunspots are found in the sun’s photosphere. They have a strong magnetic field and are cooler and darker than other areas of the sun. They can last up to a few months and come in different sizes. They appear in cycles and sometimes none can be seen.

Gas Flowing Around the Sunspots
Gas Flowing Around the Sunspots. Image credit NASA.

Different Parts on the Sun Rotate At Different Speed

The sun is composed mainly of hydrogen gas.  It is not solid like our Earth but is a ball of plasma. Due to this,  different parts of the sun rotate at different speeds. This is known as differential rotation. For example, parts lying at the equator rotate faster and complete one rotation in 25 days while parts located at the poles can take 36 days to complete one rotation. Astronomers believe the interior of the sun composed of the core and convective zone spins like a solid body.

Where Does the Sun Get Its Energy From?

The core of the sun is extremely hot and has very high pressure. These conditions support nuclear fusion where protons fuse to form helium atoms and release large amounts of energy using hydrogen as the fuel. This is the source of the sun’s energy.

The Sun’s Atmosphere Is Hotter than Its Surface

Given that the sun is the source of all the energy we have on earth, it must be very hot itself. In fact, the surface of the sun can get as hot as 6, 000 Kelvian (K). This is not even the hottest part.

The part of the atmosphere just above the surface of the sun is known as the chromosphere and temperature here can reach as high as 100,000K. A more distant atmosphere called the corona is even hotter than this with temperature reaching 1 million K.

Recent discoveries show jets of plasma bursting like fountains from the surface of the sun at very high speed. These jets heat up the corona making it hotter than the surface.

Structure of the Sun
Structure of the Sun including the Corona. Image credit Enchanted Learning.

The Sun Is Continuously Heating Up and Will Absorb the Earth in About 7 Billion Years  

The sun is slowly heating up and in about 5-7 billion years will have heated up so intensely that liquid water won’t exist on the surface of the earth and life on Earth won’t be anymore. The surface of the Earth will be scorched and uninhabitable.

Currently, the sun is classified as a Yellow Dwarf type of star. It will then become a Red Giant and eventually cool down and become a White Dwarf.

The Sun Emits Particles That Cause Radio Interferences and Other Effects

The sun emits a low density stream of charged particles composed mainly of electrons and protons and this stream is known as solar wind. The emitted solar wind and high energy particles are responsible for power line surges, radio interferences and aurora borealis also known as The Northern Lights. The solar wind is also responsible for the characteristic tails of comets and altering the trajectory of spacecrafts.

Once or Twice Every Year, the Moon Blocks the Sun from View on Earth

Viewed from the earth, the moon and the sun appear to be of the same size. The moon goes around the earth in almost the same path that the earth follows around the sun. Due to this, the moon sometimes comes between the sun and the earth and a solar eclipse occurs.

If the moon only covers a section of the sun, it is called a partial eclipse. If the entire sun’s disk is blocked, it is a total eclipse of the sun. For a few minutes, it gets dark in the middle of the day and the solar corona becomes visible.

There Are Spacecrafts Observing the Sun Right Now

The most famous spacecraft sent to observe the sun and take pictures is the Solar and Heliospheric Observatory (SOHO). This spacecraft was built by both NASA and ESA and launched in December 1995. It is still observing the sun and sending back images to the earth. On October 2006, NASA sent a twin spacecraft STEREO to observe the sun from two different strategic points, capture its activities in 3D and make it possible to predict space weather.