Scientists have worked out when the Sun will die. It won't be any time soon. It will be in 10 billion years. The scientists are from the University of Manchester in the UK. They predict that in about 5 billion years from now, the Sun will turn into a "red giant". This is the scientific name given to a star at the end of its life. When the Sun becomes a red giant（红巨星）, its center will get smaller. Its outer layers（外层） will spread（延伸） as far as Mars. This means the Earth will be burnt and disappear. After the Sun turns into a red giant, it will become a planetary nebula(行星状星云). This is a bubble (气泡) of gas and space dust（尘埃）. The scientists say no humans will be on Earth when the Sun dies out. Humans will disappear in around one 1 billion years from now.
The Sun is still quite young in space. It is just 4. 6 billion years old. This means it is only around one third into its lifespan（寿命）.
Professor Albert Zijlstra, a scientist from the University of Manchester, explained what happens at the end of a star's life. He said,"When a star dies, gives off plenty of gas and dust into space. This reveals (揭示) the star's core. By this point in the star's life, it is running out of fuel. " He said it turns off and dies in the end.
Professor Zijlstra was happy that modern science calculate (计算)the age of stars and what will happen to them. He said we can measure the presence（存在） stars in distant galaxies（遥远星系）, and"we even have found what the Sun will do when it dies".
①The Earth will be burnt and disappear.
②Humans will disappear.
③It will become a bubble that is made of gas and space dust.
④ Mars will disappear after it.
