The sun contains, like most of stars similar in size, huge amount of hydrogen. All of that matter produces a huge amount of gravitational force that squeezes the star inwards.
In order to combat the inward crush resulting from the gravitational force, the Sun utilizes fusion power to hold itself up. This is the way the sun sustains its life and escapes collapse.
How does the sun resist collapsing?
At the Sun's core, where the crush is most extreme, Hydrogen nuclei is repeatedly pushed together and combined to form Helium. This nuclear reaction results in a huge amount of energy that pushes the outer layer of the star outwardly.
According to scientists, as long as the Hydrogen fusion reactions are functioning as they have in the past; the Sun is safe from gravity and can continue to serve as a source of heat and light for Earth.
The hydrogen fuel of the Sun can't last forever. In approximately five billion years from now, the Hydrogen at the center of the Sun will all be converted into Helium. The gravity of the sun will overwhelm and its layers will fall towards its nuclei, the heat at the core of the sun will rise as a result. This will heat the outer layers and it will expand as a result.
The sun will have become a red giant, so large that it will engulf the planet Mercury, perhaps extending to encompass the orbit of the earth.
Even if the swollen sun stretches no farther out than Mercury, however, the heat reaching earth will be from 500 to 1,000 times as great as it is today.
Oceans will boil, and life will be incinerated. Note that the heat of the sun will have started to deceases a great deal.
So we can recapitulate the following important information:
(1)The sun will collapse inwards and its heat and light will eventually fade away.
(2) The sun outer layers will be puffed out and the sun will swallow the nearby planets.
(3) The sun outer layer will reach the orbit of the earth
(4) The seas will be boiling.
The Fate of the Sun
The sun has been shining for about 4.5 billion years [source: Berkeley]. The size of the sun is a balance between the outward pressure made by the release of energy from nuclear fusion and the inward pull ofgravity. Over its 4.5 billion years of life, the sun's radius has gotten about 6 percent bigger [source:Berkeley]. It has enough hydrogen fuel to "burn" for about 10 billion years, meaning it has a bit over 5 billion years left, and during this time it will continue to expand at the same rate [source: Berkeley].
When our sun becomes a red giant, its radius will be about 100 times what it is now. Planetary nebulae are the remains of sunlike stars that have reached the end of their red giant stage. Photo courtesy of NASA Sun-Earth Day 2010
When the core runs out of hydrogen fuel, it will contract under the weight of gravity; however, some hydrogen fusion will occur in the upper layers. As the core contracts, it heats up and this heats the upper layers causing them to expand. As the outer layers expand, the radius of the sun will increase and it will become a red giant, an elderly star.
The radius of the red giant sun will be 100 times what it is now, lying just beyond the Earth's orbit, so the Earth will plunge into the core of the red giant sun and be vaporized [source: NASA]. At some point after this, the core will become hot enough to cause the helium to fuse into carbon.
When the helium fuel has exhausted, the core will expand and cool. The upper layers will expand and eject material.
Finally, the core will cool into a white dwarf.
Eventually, it will further cool into a nearly invisible black dwarf. This entire process will take a few billion years.
So for the next several billion years, humanity is safe -- in terms of the sun's existence, at least. Other debacles are anybody's guess.
By Magdy Abdalshafyhttp://www.knowmuhammad.org/articles/-/asset_publisher/2qjX/content/the-fate-of-sun-accoeding-to-science-and-quran?redirect=http%3A%2F%2Fwww.knowmuhammad.org%2Farticles%3Fp_p_id%3D101_INSTANCE_2qjX%26p_p_lifecycle%3D0%26p_p_state%3Dnormal%26p_p_mode%3Dview%26p_p_col_id%3Dcolumn_2%26p_p_col_pos%3D1%26p_p_col_count%3D2