Looking up at a Chinese night sky Confucius poetically said: “Stars are holes in the sky from which the light of the infinite shines.” Scientifically, we now know that the stars are actually giant balls of hydrogen converting to helium in a nuclear fusion process and kicking out huge amounts of heat, light, plasma, particles and radiation in the process. But is our Sun a “normal” size and “type” of star and how does it compare with all the other 200 billion trillion (2 with 23 noughts!!!) stars out there?

Our Sun is smaller than most stars we can see because the brightness of stars relate to their mass. Nearly all stars that are visible are large ones as in the image showing huge variations in size of some well-known stars. Stars as bright as the Sun are very hard to see beyond the distance of several thousand light years. However, the Sun is larger than most stars actually out there as nearly all stars are Red Dwarfs that are much smaller in mass than the Sun and they get very hard to see beyond the distance of several dozen light years. This is where the BBC sci-fi comedy “Red Dwarf” gets its name! As the name suggests they are small and red and keep burning until they have transformed all their hydrogen into helium, finally becoming a hugely dense White Dwarf. So 95% of the stars we see in the night sky are brighter/larger than the Sun, but 95% of all stars are dimmer/smaller than the Sun so we see almost none of those dimmer stars. 

Like people, stars have a lifespan, some shorter than others and evolve ending up in a different state depending on their size and internal processes. As in the acting profession, some aspiring stars, never actually get hot enough to ignite into fully-fledged stars, and simply cool off and fade away and are known as Brown Dwarfs. Stars like our Sun eventually swell into Red Giants (bye-bye planets!) before puffing away their outer shells into a colourful nebula while their cores collapse into a White Dwarf.

Some of the largest stars in the Universe are young, blue Supergiant Stars. Unlike a relatively stable star like the Sun, Supergiant Stars are consuming hydrogen fuel at an enormous rate and will consume all the fuel in their cores within just a few million years. They live fast and die young, detonating as supernovae; completely disintegrating themselves in the process, leaving behind an unbelievably dense Neutron Star or Black Hole. The biggest star identified is a bright red supergiant UY Scuti. Located 9,500 light years away in the constellation Scutum, estimated to be huge enough to hold 5 billion Suns. Your brain may now go supernova!

Glynn Bennallick