What are the changes that are likely to take place during the life of our sun?

Answer 1

After about 10 Billion years, the sun will have used up its supply of Hydrogen as a fuel source. This will disturb the equilibrium and it will start to expand rapidly (to fill the space in the solor system up to about Earth's orbit) and turn a red colour - this is the Red Giant phase.

The sun may then be able to start using Helium as fuel and return to normal size for a couple of billion years. When the He Source runs dry it will return to a larger Red Giant phase, engulfing up to the orbit of Mars, before collapsing and dying out as a cooling, but bright Dwarf.

EDIT: To the person below me - I have a degree in physics, including Stellar Physics - trust me on what I say. There will be two Red Giant stages - one after the Hydrogen burning phase and one after the Helium burning phase.

Answer 2

Stuart T, the sun isn't going to expand twice, when it runs out of hydrogen, it will expand perhaps as far as the orbit of Mars, then collapse into a white dwarf.
Once the energy in the sun is used up, it has no more. That's like saying you can explode an atomic bomb twice.
The sun has approximately 5 billion years left of fuel, but since it isn't a constant star, it could go long before that. All theories of the life times of stars are still only theories.
It also doesn't have enough mass to become a red giant.

Answer 3

it will undergo the red gaint phase n then become a dwarf star and then ultimately a black dwarf and end its life. but as soon as sun enters the red gaint phase(500 million years after) it will engulf mercury and venus and maybe earth. but if it engulfs venus n mercury then the distance between earth and sun will decrease and more heat will reach earth and thus life will not exsist then on earth.

Answer 4

same as with people: use energy, expand, and die.