One day the sunshine will run out, and our Sun will die. A star’s life consists of stellar birth, aging and death, a pattern similar to that of a human. The Sun is almost five billion years old, and it will have used up all its fuel in about five billion years.
One day the sunshine will run out, and our Sun will die. The death of our Sun will be exciting, even though the Sun is not massive enough to blow itself into pieces in a beautiful supernova explosion. Like all stars, our Sun follows a life cycle, which depends on its mass. A star’s life consists of stellar birth, aging and death, a pattern similar to that of a human. The Sun is almost five billion years old, and it will have used up all its fuel in about five billion years. The Sun will end its life in the centre of beautiful planetary nebulae (planetary nebulae has nothing to do with planets), a white dwarf in colourful veil of gas. The Sun will cool and fade; eventually it will no longer be visible. Our Sun has become a black dwarf.
There are different types of stars, our Sun is a yellow dwarf, and they live about ten billion years. The name yellow star is not a good description of the stars in this category, as the stars actually range in colour from white like the Sun, to only slightly yellow. There are seven main types of stars, and they are classified by the elements they absorb – their spectra.
The Sun was born in the star-forming or pre-stellar nebulae, about 4.6 billion years ago. Stars are formed in huge clouds of dust and gas that collapse under gravitational forces. Formations of gas, dust clump together to form larger masses, and eventually they will become big enough to form stars. The remaining materials are believed to form planets, moons, dwarfs planets (such as Pluto), asteroids and other solar system objects. A famous image of a star nursery is NASA’s the “Pillars of Creation”.
Our Sun is a hot body of glowing gas, like a giant gasbag. It contains two gases hydrogen and helium and it is the hydrogen in the Sun”s core that one day will run out. Nuclear fusion is a process when two atomic nuclei are forced so close together that they become one, and they form another element. The Sun fuses hydrogen atoms together to make helium atoms in its core, and it grows brighter when more helium accumulates in its core. Energy is given out in nuclear fusion, and it makes the Sun shine.
All stars will run out of hydrogen within their cores, and the bigger a star is, the quicker it will die. This might seem odd, but massive stars exhausts their fuel supply quicker. The outer layers of a star still contain hydrogen, and this causes the star to expand and grow more luminous. As the Sun grows old, it will expand into a red giant.
The Sun’s core runs out of hydrogen and it will begin nuclear reaction with helium instead, fusing helium atoms to from carbon. Helium builds up in the core, the core becomes hotter and hotter, and the remaining hydrogen will fuse faster and faster. As a result, the Sun’s surface will be hotter. Increasing the temperature prevents the Sun from collapsing in on itself when the supply of hydrogen dwindles. The increase in temperature raises the rate at which nuclear reactions occur and makes the Sun brighter. The Sun in its present form is getting ten per cent hotter every billion years.
Our Sun will become a bloated version of its former self. When the Sun has used up its fuel, it will no longer be able to support the weight of its inner layers, and they will begin to collapse toward the core, eventually producing a small, dense, cool star called a white dwarf. The white dwarf, approximately the size of the Earth, will shine for billions of years. White Dwarfs are not big enough to continue nuclear fusion reactions, and the Sun will slowly fade away. The Sun will be a cold, dark black dwarf – essentially a dead star.
What Will Happen to the Earth?
Mercury and Venus will be engulfed by the Sun. Astronomers are not sure what will happen exactly to the Earth, it might be eaten up as well. If the Sun does not consume the Earth, temperatures on Earth will become extremely high, and there will be no water left. There is also the possibility that the Sun could switch galaxy. The merger between the Andromeda Galaxy and the Milky Way is predicted to take place before the Sun burns out – within 5 billion years.