The Sun, the largest fusion reactor in the Solar System, but for how long?

Authors Avatar



The Sun, the largest fusion reactor in the Solar System, but for how long?

Statement of Aim

The Sun is globe of intensely hot gas, it is self luminous and produces energy by means of nuclear processes that occur deep within it.

A substantial amount of this energy harnessed over millions of years has provided life here on planet Earth and continues to do so.  But what if the life cycle of the Sun comes to an abrupt end.  Will life cease to exist?  The explosion of this star in the universe may be as a whole utterly insignificant but it could wipe out the human race!

The aim of this report will be to carry out an investigation into the Sun, its beginnings, its state at present and its future. It will include a thorough analysis of the thermonuclear reactions that take place inside the Sun.  To conclude with, my report will correlate existing information to find an estimate of the life expectancy of the Sun.      

How information and particular resources were identified

With recent study in to the phenomenon of particles within the nucleus of an atom, I decided to research further in to the actions of such particles in thermonuclear reactions that take place inside the Sun.  I started by using the Internet and the Nasa website.  This proved to be most useful.  I also gained the chance to look at a lecturer’s notes.  By using the Internet I was able to locate particular books and research experiments that proved to be my most valid source of information.


        Over three centuries ago Copernicus, Keplar and Newton led a revolution in our understanding of the Universe, when the Solar System was revealed as a simply dynamic entity, Astronomy at that time was concerned with positions and motions and the Universal Law of Gravity.  The nature of stars and the planets was unknown, awaiting revelation in the age of telescopes and space probes.

        In just over three decades we have been presented with an overwhelming quantity of photographs and other information about the Solar system, which has transformed our understanding of the Sun.  Never again would there be such a period of expansion.

        We have learned much more about the Sun, without which the Earth and other planets could never have come into being.  It is a normal main sequence star, but not as constant and unchanging as used to be thought.    

The Sun and its Surroundings

The Sun is a very ordinary star and only appears so glorious because of its relative proximity to the Earth.  The distance between the Sun and the Earth on average

150,000,000 km (1 Astronomical Unit).  The Star system to which the Sun belongs is known as the Galaxy (or Milky Way).  It contains at least 100,000 million stars, which are of very different types.  Some are much more powerful than the Sun, others are feeble by comparison.  They have a wide range of surface temperatures, very hot stars such as Vega and Rigel in Orion glow white or blue.  The Sun, however with a surface temperature of about 6000 °C is yellow; while cooler stars such as Betelgeux in Orion are orange or orange-red.

Stars only exist in galaxies.  The Milky Way is about 100,000light years in diameter (1 Light Year ≈ 9.5 x 10 15   m).  The Sun, with its attendant planets lies close to the edge of one the spiral arms of the Milky Way.  The Milky Way is known to rotate and the Sun takes about 225,000,000 years to complete one journey around the galactic centre.

The core temperature of the Sun is in the order of 14,000,000 ° C, and the absorption or emission of radiation by the constituents of the Sun produce lines on the spectrum of light received from the star.   By this method of spectral classification, stars are said to be of a particular colour.  The surface temperature of the Sun is also linked to the stage of stellar evolution they have reached.  The course of which depends largely upon the initial mass of the original nebular material from which the Sun forms.

The Sun is a fairly average star.  It is accompanied by a planetary   system comprising nine planets and various bodies.  The planets move in orbit around the Sun and this is proof of its gravitational interaction with the bodies.

The law of gravitation can be used to determine the field strength or potential at any point in the field produced by a spherical mass such as the Sun.  The field of the Sun is the same as if the mass were concentrated at its centre.


                                                 Fig 1 A Radial field                                  



The gravitational force F of the Sun on a planet such as the Earth can be given by:

Eq.1                        F = G M m


        R 2         where R is the distance from the centre          

                                                    of the Sun ( core) to the centre of the Earth


Join now!

                                R= 1.503 x 1011 m


Therefore:  F= 7.929 x 1044 N                              Mass M of the Sun  1. 9891 x 1030  kg


                                             Mass m of the Earth 5.9742 x 1024 kg

                                     Gravitational Constant 6.6720 x 10-11 N m2 kg-2

This is a considerable amount of force!  We can test the units of G by rearranging    Eq .1 , to make G the subject:


This is a preview of the whole essay