Unfortunately, the amount of fuel inside the Sun is limited. You can't see it, but in fact, that huge light bulb in the sky we call `Sun' shrinks and cools down a tiny little bit every second. The Sun is `middle aged'. In another 5,000 million years, it will run out of hydrogen.
Long before, we will notice the consequences. On the one hand, the Sun will get brighter and warmer. On the other hand, as the Sun shrinks and becomes less heavy, its gravitational pull on the Earth will loosen. Consequently, the orbit of our planet and all other planets in the solar system will widen.
Okay, so an earthly year will be several weeks longer. But don't mistake, there's a downside here. It will get colder. And not just a little bit. Within `only' several billions of years, Earth will become an icy, permafrost planet, where it will be hard to survive.
Well, we're still lucky, really. When the Sun eventually runs out of hydrogen, the nuclear reactions inside the Sun's core will stop. There will be no explosive force pushing outwards from the heart of the Sun anymore. The Sun will collapse, pressed together by its own gravity.
Subsequently, temperatures inside the Sun will rise even more. And, lucky we, there will be another nuclear reaction sparking off. The Sun will start fusing helium into carbon and hydrogen this time. KABOOM! This will prevent the Sun from collapsing any further. Finally, we will have warmth again.
But wait, we're in trouble. A nuclear power plant that runs on helium gives off a hell of a lot more energy and heat than one run on hydrogen. The new, immense power of the Sun's core will literally blow up the Sun. The Sun will grow, eating up several planets: first Mercury, then Venus. And next on the menu, yes, Earth.
The absorbing 1961 movie The Day The Earth Caught Fire gives a pretty good picture of what it will be like. Sure, it will become quite hot. Rivers will evaporate, causing dense, hot fogs. The polar ice will melt, causing oceans to rise and entire countries to flood. But then, the sea will evaporate as well. Long before the solar surface reaches our planet, we will simply be barbecued to death. Sadly, there is no happy ending. Eventually, Earth will be swallowed by the growing Sun. Our planet will burn up in its ultra hot outer layers.
Of course, we still have some 5,000 million years to come up with a solution for this nasty problem. For one thing, we might evacuate, or even find a way to move our entire planet away from the Sun. But even then, it's highly unlikely we will enjoy the Sun as much as we once did. Since the Sun has expanded so much, its outer parts will cool down. The Sun's surface will become cool, deep red. It will be a Red Giant -- `giant' being just the right name for an object that just ate up our planet.
Posts
