Stars, Singularities And The Incomprehensible Size Of The Universe
After flying past Pluto to take high-resolution images and record crucial scientific data on the dwarf planet, NASA’s New Horizons probe is now at the edge of our Solar System. But that, of course, is not the end of the story.
The Solar System is just a small part of the Milky Way galaxy. This in turn only makes up a tiny bit of the whole Universe, the scale of which is so vast it defies the imagination. Even using light to measure distance (since nothing can cross the vastness of interstellar space faster), only a fraction of the Universe is visible to us – the part of the Universe from which light has had time to reach Earth since the Big Bang. Beyond what we are able to observe (an area approximately 93 billion light years across), the true size of the Universe is unknown. It could potentially be infinite.
Even though we are only able to observe only a tiny fraction of the Universe, there is much out there to grab our attention. For one thing, space is packed with stars of every size, colour, and brightness.
Dwarf stars, the smallest type of solar body, can measure less than a thousandth of the volume of our own Sun. They also tend to be rather dim, depending on their colour. A red dwarf, for instance, pales in comparison to our orange Sun. Yet despite being the fraction of the size of their red cousins, white dwarf stars glow much more brightly. These are the tiny, dense remnants of giant stars that have lost their outer layers.
Calling giant stars “giant” is not an exaggeration, either. The typical giant star is over 200 times wider than the Sun. Its cousins, the hypergiant and the supergiant, can be up to 2000 times wider and 8 billion times greater in volume than our tiny star. But while these giant stars can glow billions of times brighter than the smallest stars in the Universe, their brightness comes at a cost. Hot, bright giants will have much shorter lifespans than dwarf stars, since they burn though their nuclear fuel much faster.
While some giants will end their lives as white dwarf stars, some will collapse in on themselves after death, unable to resist the force of their own gravity. The process can take mere milliseconds, leaving a former giant star’s core infinitely smaller than an atom – an object known as a singularity, or the heart of a black hole.
The impossibly small singularity of a black hole has an infinite density. Anything that strays within a certain distance of the singularity is doomed to get pulled in by gravity and disappear forever. This point of no return is known as an event horizon – the boundary which marks how closely you can safely get.
But if you’re worried that we might all be in danger of being drawn into a singularity, don’t fret – according to astronomers, the nearest suspected black hole is located around 3,000 light years from Earth.
Knowledge Encyclopedia Space! reveals jaw-dropping 3D images of planets, stars and much more. Perfect for projects or kids interested in the wonders of space, covering every (known) inch of our solar system, galaxy and universe, the book is fully up-to-date and features the latest stunning images from NASA and Hubble.