Our Solar System emerged from mixed fragments composed of lingering relics from the long-dead, nuclear-fusing furnaces of older generatons of stars. Our Sun (like its missing, sparkling sisters), was born tucked within a frigidly cold and dense blob, secreted within the ruffling, whirling folds of a giant, dark molecular cloud. Although it may seem counterintuitive, things have to get very cold before a new, fiery, searing-hot baby star can be born. The star-birthing, dense blob eventually collapsed under the intense pull of its own gravity–thus giving birth to a brand new baby star. In the hidden depths of these vast and dark molecular clouds composed mostly of gas, with much smaller quantities of dust, fragile and delicate threads of material gradually merge and then clump together–growing in size for hundreds of thousands of years. Finally, squeezed relentlessly by the merciless crush of gravity, hydrogen atoms tucked within this clump rapidly and dramatically fuse, lighting a raging stellar fire that will continue for as long as the new star “lives”.
Our Star’s diameter is about 864,337.3 miles, which is approximately 109 times that of Earth, and its mass is about 330,000 times that of Earth. Our Sun accounts for approximately 99.86% of the mass of our entire Solar System. About three-quarters of the Sun’s mass is composed of hydrogen (about 73%), and the rest is mostly helium. (25%)–with significantly smaller quantities of heavier atomic elements, such as oxygen, carbon, and neon.
Our Sun is classified as a G-type main-sequence star, based on its spectral class. A star, like our Sun, is a still “living” star on the hydrogen-burning main-sequence of the Hertzsprung-Russell Diagram of Stellar Evolution, and it is informally (and somewhat inaccurately) frequently referred to as a yellow dwarf. However, our Star’s light is actually closer to white than it is to yellow. It was born about 4.6 billion years ago from the gravitational collapse of matter within its star-birthing molecular cloud. Most of the collapsing material collected at the center, while the rest flattened out into an orbiting disk that eventually became our Solar System. The central mass grew searing-hot and dense, and it ultimately initiated nuclear-fusion in its core. Our Sun was born this way–and all other stars also form as a result of this process.
Our Sun is currently enjoying an active, roiling midlife, and it has not changed much for more than four billion years. It will probably remain in this stable condition for another five billion years or so. Our Sun currently fuses approximately 600 million tons of hydrogen into helium every second, fusing about a million tons of matter into energy every second as a result. This energy, which can take between 10,000 and 170,000 years to escape from the searing-hot core, is the origin of our Star’s dazzling light and ferocious heat. But, in about 5 billion years, when hydrogen fusion in our Sun’s core has diminished to the point in which it can no longer remain in hydrostatic equilibrium, its looks will change. At this point, the core of our Star will undergo a dramatic increase in density and temperature, even as its outer layers balloon in size. Our bloated crimson Sun will eventually evolve into an enormous red giant star that will engulf Mercury and Venus–and possibly Earth as well. But even if our dying Sun, in its cannibalistic red giant phase, does not engulf our doomed planet, it will certainly render Earth uninhabitable.
When our dying Star finally reaches the end of that long stellar road, it will cast off its outer gaseous layers and evolve into a dense, cool stellar corpse called a white dwarf star, that can no longer produce energy by way of the process of nuclear fusion. Our Star will perish peacefully, as well as beautifully. The new and ghostly white dwarf will be surrounded by a beautiful shimmering, glimmering, multicolored shroud, called a planetary nebula, that is composed of what was once our Sun’s outer gaseous layers. Indeed, planetaries are so beautiful that astronomers frequently refer to them as the “butterflies of the Universe.” mkvzone