The Sun

Updated: Sep 4, 2020

- brought to you by The Spacestellar


Introduction : The Sun is the star at the centre of the Solar System. It is a nearly perfect sphere of hot plasma, with an internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometres (864,000 miles), or 109 times that of Earth, and its mass is about 330,000 times that of Earth. It accounts for about 99.86% of the total mass of the Solar System. Roughly three-quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. It formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the centre, whereas the rest flattened into an orbiting disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core. It is thought that almost all stars form by this process.

Compositions : The Sun is composed primarily of chemical elements such as hydrogen and helium. At this time in the Sun's life, they account for 74.9% and 23.8% of the mass of the Sun in the photosphere, respectively. All heavier elements, called metals in astronomy, account for less than 2% of the mass, with oxygen (roughly 1% of the Sun's mass), carbon (0.3%), neon (0.2%), and iron (0.2%) being the most abundant.

Sun Facts :

  • The light from the Sun takes 8min 19sec to reach earth.

  • The energy produced on the sun is due to the thermonuclear fusion process.

  • The Sun has all the colours mixed together, this appears white to our eyes.

  • The Sun is composed of hydrogen (70%) and Helium (28%).

  • The Sun is a main-sequence G2V star (or Yellow Dwarf).

  • The Sun is 109 times wider than the Earth and 330,000 times as massive.

  • The Sun’s surface area is 11,990 times that of the Earth’s.

  • The distance between the Earth and the Sun is an Astronomical Unit (AU).

  • The Sun revolves around the centre of the Milky Way galaxy in 230 million years.

  • The Sun is an almost perfect sphere.

Size comparison of Sun and other planets
Size comparison of Sun and other planets

Some other facts :

  1. One million Earths could fit inside the Sun. A hollow Sun would fit around 960,000 spherical Earths. If squished inside with no wasted space, then around 1,300,000 would fit inside. The Sun’s surface area is 11,990 times that of the Earth’s.

  2. The Sun contains 99.86% of the mass in the Solar System. The mass of the Sun is approximately 330,000 times greater than that of Earth. It is almost three-quarters Hydrogen, whilst most of the remaining mass is Helium.

  3. The Sun is an almost perfect sphere. There is a 10-kilometre difference between the Sun’s polar and equatorial diameter. This means it is the closest thing to a perfect sphere that has been observed in nature.

  4. The Sun will consume the Earth. When the Sun has burned all its Hydrogen, it will continue to burn helium for 130 million more years. During this time, it will expand to the point that it will engulf Mercury, Venus, and the Earth. At this stage, it will have become a red giant

  5. The Sun will one day be about the size of Earth. After its red giant phase, the Sun will collapse. It will keep its enormous mass with the approximate volume of our planet. When this happens, it will have become a white dwarf.

  6. The temperature inside the Sun can reach 15 million degrees Celsius. Energy is generated at the Sun’s core, by nuclear fusion, as Hydrogen converts to Helium. Hot objects expand, the Sun would explode if it were not for its enormous gravitational force. The temperature on the surface of the Sun is closer to 5,600 degrees Celsius.

  7. Light from the Sun takes eight minutes to reach Earth. The Sun is an average distance of 150 million kilometres from the Earth. Light travels at 300,000 kilometres per second. Dividing one by the other gives us an approximate time of 500 seconds (or eight minutes and 20 seconds). Although this energy reaches Earth in a few minutes, it will already have taken millions of years to travel from the Sun’s core to its surface.

  8. The Sun travels at 220 kilometres per second. The Sun is 24,000-26,000 light-years from the galactic centre. It takes the Sun 225-250 million years to complete an orbit of the centre of the Milky Way.

  9. The distance from the Sun to Earth changes throughout the year. This is because the Earth travels on an elliptical orbit around the Sun. The distance between the two bodies varies from 147 to 152 million kilometres.

  10. The Sun is middle-aged. At around 4.6 billion years old, the Sun has already burned off about half of its store of Hydrogen. It has enough left to continue to burn Hydrogen for approximately 5 billion years. The Sun is currently a type of star known as a Yellow Dwarf.

  11. The Sun has a very strong magnetic field. Magnetic energy released by the Sun during magnetic storms causes solar flares. We see these as sunspots. In sunspots, the magnetic lines twist and they spin, much like a tornado would on Earth.

  12. The Sun generates solar wind. The wind is a stream of charged particles. This travels at approximately 450 kilometres per second through the solar system. Solar wind occurs when the magnetic field of the Sun extends into space.

  13. Sol is the Latin for Sun. This is where the word “solar” comes from, which is used to describe things that are derived from, related to, or caused by the Sun

Feature off Sun :

Sunspots :

Sunspots are areas of the Sun’s surface that appear darker than the surrounding areas, this is because they are cooler. They form in areas of strong magnetic activity that inhibit heat transfer.

Solar Flares :

When the magnetic fields near sunspots cross, tangle or are reorganized, an explosion of energy can be released. Intense solar flares can interfere with radio communications on Earth.

Satellites of Sun :