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Time, the Universe and the Whole Darn Thing!
Part One: The Future of the Earth

By Allan Eastman

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Sun, Sun, Sun, Here It Comes...

"Pillars" and "Mountains" of Star Formation

Stardust...”We’re all made of stardust”.

©NASA/courtesy of nasaimages.org

At the moment though, you could say that we live in a Universe of Stars. They are the defining feature of the Cosmos that we see but it won’t always be that way. So it’s lucky that we have one nearby, our good friend the Sun, or Sol as it is more formally known. Everything about our existence as a planet and a species has to do with this fiery orb in the sky and the long term life of both will be very much affected by the ultimate evolution of our star.

Our local galaxy, the Milky Way began to form as a revolving accretion disc of gases and matter around its Black Hole about 8.3 Billion years ago and our solar system began to form in a similar but localized manner about 3.3 Billion years later, or about 5 Billion years ago. The massive density of compressed gases and the flotsam and jetsam from the previous stars’ super novae at the center of our solar system heated up under frictional gravitational forces and pressure and eventually ignited, starting the familiar nuclear chain reaction of fusing hydrogen into helium and producing massive amounts of energy in the process.

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The dense clouds of gas and matter rotating around the gigantic gravitational attraction of the Sun started to form into proto planets shortly thereafter. The planets made up of heavier densities of matter like iron - Mercury, Venus, Earth, Mars – settled into orbits closer to the Sun whereas the planets composed of lighter material became the far larger Gas Giants – Jupiter, Saturn, Uranus and Neptune – orbiting further out.

The Sun is a so called Late Generated Star because it incorporates within it the debris from those previous generations of early Super Massive stars. It is about 1.391 Million kilometers in diameter (864,000 miles). Its surface gravity (not that you’d want to be standing there) is 28 times that of Earth’s and about 1 Million Earths would fit comfortably inside its volume.

In the observable Universe, about 80% of the stars are smaller than the Sun and 10% are larger, so it is in the 80th percentile when it comes to size. The Sun is basically a controlled nuclear explosion – the immense pressure wanting to be released is repressed by its equally immense gravity.

The nuclear fusion going on in the Sun’s core transforms about 700 Million metric tons of hydrogen every second into 6.95 Million tons of helium. The remainder is converted into energy according to Einstein’s formula E=mc2, resulting in about an awesome 400 Trillion Terawatts of nuclear power a second. By way of comparison, during the entire year of 2006, the TOTAL energy used on Earth was 16 Terawatts. Some of this solar energy reaches us in the form of the very useful radiations of heat and light that sustains life on Earth.

You may be relieved to know that the Sun is not going to go Super Nova anytime soon. In fact, the Sun will never become one of those stupendous cosmic explosions. It simply isn’t big enough, or more properly, isn’t massive enough to have that titanic core collapse which precipitates the Nova detonation once it gets down to fusing iron. However, the evolution of the Sun does have some awesome changes in store and many of them are less than pleasant when viewed from Earth’s perspective. Our human Fate – if we last long enough to face it – is irrevocably intertwined with the Fate of our star.

Pretty much every early Human society looked at the Sun as being Prime among the Gods. But they really had no notion of just how incredibly powerful it is or what it is going to do to us. The word “Disaster” derives from the Latin for “Bad Star” and that is what we will literally be looking at eventually. But we’ll get back to that in a moment after a brief digression homeward.

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