Derek Shirlaw | Astronomy | Stars
The Sun is our closet star, but, it's just one of an intangible number of stars in our observable Universe.
Stars are like giant nuclear reactors, burning gases like hydrogen and helium as their fuel, and producing massive amounts of energy in the process.
Stars are born, grow old and die. They effectively recycle matter.
Our local star, the Sun, is a fairly average middle-aged star (a main sequence star) that is about halfway through its life at about 5,000 million years old. Don't worry too much then about what's going to happen to us when it dies as we won't be around!
In its glittering finale, our Sun, after having used up just about all of its fuel, will expand to be a red giant, in all likliehood engulfing the planets of Mercury, Venus and Earth (curtains for us if we're still clinging on to this planet!). The outer layers of hot gas will evenutally disperse leaving behind a white dwarf that'll continue to cool and fade over billions of years.
Other stars are destined for even greater death throws and impressive endings. These are stars with masses about 10times as great as that of our Sun. These will swell into red supergiants that simply can't sustain such a massive core and explode in what is termed as a supernova. What happens next depends of the size of the core. If it's of relatively small mass it'll be crushed into a region spanning just 15km across known as a neutron star. If the core is about twice the mass of the Sun, its own gravity will collapse it further into a black hole.
