It must be a woman who is first on Mars

I guess that might be possible as well, what a sad, but perhaps a fitting end, wiped out by war in space   

That is a very important thing for equality, fairness and the progress of women. A man first walked on the moon. Valentina Tereshkova could have done that, if she had been given the opportunity. 

The sun generates its heat by a process of nuclear fusion in it's core where in a series of nuclear collisions involving atomic nuclei and electrons, hydrogen is gradually transformed into helium, a process that converts part of the original mass into massive amounts of energy. But as the helium content in the core increases the sun gradually burns hotter. This is a very slow and gradual process, but it is definitely chucking out more heat than it was half a billion years ago. It is currently about 5 billion years old which is a little over a third of the age of the universe thought to be a bit under 14 billion years old. It has been slowly heating up ever since it was born and will continue to do so. Over many tens or hundreds of millions of years this becomes very noticeable but is far too minute to be noticeable on human time scales so is not the phenomenon responsible for climate changes in the last  few thousand years. Though more temporary fluctuations in output related to changes in it's magnetic field might well have been a factor, as well as any wobble in the earth's axis of spin or changes in the composition of its atmosphere and suchlike.

Anyway, I digress. The sun will continue converting hydrogen into helium at its core, getting progressively hotter over geological timescales as it does so. Until in about another 5 billion years or so the core becomes choked up with helium with little hydrogen left to burn resulting in a temporary diminution in the rate of nuclear fusion with less outward pressure to hold off the inward pull of gravity. At this point the core and the layers immediately about it begin to contract under the weight of gravity, which in turn heats it up further. Layers outside the core then become hot enough to begin fusing hydrogen into helium there, whilst the helium in the core becomes hot enough to start fusing into carbon. This creates more powerful outwards pressure sufficient to almost overwhelm gravity and the outer layers of the sun get blown out into a vastly larger area.  The surface area becomes cooler, hence red instead of yellow. Which is why this type of star is known as a red giant. But it is still several thousand degrees Celsius at the surface. When the sun becomes a red giant in about 5 billion years it will grow so large that it will entirely engulf the inner two planets Mercury and Venus. Scientists are uncertain whether it will grow large enough to engulf earth too. If it does our planet will also be destroyed. If it doesnt our planet will be so close to this vast star that it will be melted into a ball of molten rock or metal. Life here would be impossible.

Eventually the remnant core will use up all the helium turning it into carbon, whilst in a shell around it the hydrogen will have been converted into helium and nuclear fusion winds down again. By this time the outer layers have been blown off entirely to form a ring of gas around the shrinking core. This is known as a planetary nebula because it resembles a planetary disc in telescopes. As the spent fuel near the core shrinks it of course gets hotter again, the bigger the star the hotter it gets. In stars much larger than our sun the carbon gets so hot that it fuses into heavier and heavier atomic elements, like oxygen and silicon and eventually in the end iron. The bigger the star the faster this happens. When iron  forms a core, further fusion becomes impossible and a massive core collapse takes place along with all the surrounding layers. These other collapsing layers rapidly grow so hot that fusion of different elements into others begins throughout the star causing a massive supernova that blows the star apart. Such is the energy involved in such a short period of time that a single supernova can outshine an entire galaxy full of a hundred million stars. The colossal energy involved is so great that it fuses iron into heavier elements still, even though this uses energy rather than creating it.

All the elements we know on earth today that are heavier than iron - gold for example - were created in the explosions of massive stars, the dust spreading throughout the galaxy and becoming part of vast dust and gas clouds in space, the collapse of which creates new stars. Our sun formed on one such collapsing gas and dust cloud, itself already seeded with dust grains of heavy elements created in massive earlier stars and their explosions.

The cores of such massive stars are not blown apart with them but continue to rapidly collapse under the weight of their own mass. So powerful is the gravity that all electrons and protons are squeezed together to form neutrons with no atomic space left between them. These are neutron stars consisting of nothing but densely packed neutrons which can contain more mass than our sun squeezed down into something only a few miles across. A teaspoon full of this material would weigh millions of tons. And as spinning objects spin much more rapidly as they contract, something so small with so much mass can spin many thousands of times a second. These weird stars are fiercely magnetic and send out a continuous blast of intense radio waves from their poles. If they are aligned in such a way that this blast of radio waves reaches us with every spin, we detect them in the form of regular powerful bursts of radio waves or pulses. This is why when first detected they were known as pulsars. 

When a core is crushed into a neutron star the powerful nuclear forces involved are sufficient to prevent any further collapse, but only if the mass does not exceed a certain point known as the Chandrasekhar  limit. If the mass is greater than this even a neutron star cannot survive and it collapses into a black hole.

But I have been seriously digressing again. The mass of a star like our sun is not great enough for it to heat up enough due to gravitational collapse to burn much carbon into anything heavier. Nor is it great enough for the core to collapse into a neutron star. Instead it will collapse into a compact object perhaps the size of a planet to become a white dwarf, slowly cooling over billions more years.

The earth, if it has survived at all will now be a cold and barren rock in space, all life upon it long gone.

But if the Sun is destined to become a red giant in 5 billion years or so, it does not mean that life on earth is destined to survive here for that long. Because the sun is getting gradually hotter it will destroy life here much sooner. It will probably be becoming uncomfortably hot within half a billion years and it is reckoned that by about 1 billion years from now, 2 billion years at most, the heat will trigger a runaway greenhouse effect and we will become another hell hole like Venus. But as things get too hot here, other bodies much further out will be warming up too, and if there survives an intelligent species on this planet capable of travelling elsewhere, Mars, and later the moons of Jupiter might become a possible oases for a time. But eventually life throughout our solar system will be impossible anymore unless in  artificial underground areas on rocky bodies.

I think the prospect is so distant it doesn't itself demand any focus at all. Either our exit from the solar system is (more or less) impossible, or following our nose will lead us out in a time frame of billions of years. If it gets to the '1 million years left' mark, we can start rubbing our beards and drinking coffee over the matter. Of course, there will be no such ting as humans then, so all of this talk of late nights with coffee is entirely fantasy.

I suspect the voyager missions and all those handy diagrams were a mistake born of an age of optimism. The optimism here is gargantuan, cosmic in scale.