Take two 20¢ coins, one representing the Milky Way and the other the Andromeda galaxy. Place them on a table and separate them by 25 times their individual diameter. To scale, this will be the relative distance between them in space. However, if one of those coins now represents the sun and the other is an apple pip representing the smaller size of the nearest star – Proxima Centauri – the distance between the two will shock you; it would be 776 kilometres away – more than the distance from Melbourne to Adelaide. As you now realise, within galaxies the space between stars is vast. The Voyager 1 spacecraft on its way out of the solar system at a speed of 17 kilometres per second – many times faster than a bullet – would take nearly 74,000 years to travel the 4.2 light years to Proxima Centauri.
This star was not discovered until 1915, by Scottish astronomer Robert Innes while he was working at an observatory in South Africa.
Called Proxima Centauri because of its proximity, it’s sometimes referred to as Alpha Centauri C, because it’s thought to be a far-flung third member of the Alpha Centauri star system – which is seen as a single star with the naked eye and is the brighter of the two ‘‘pointers’’ to the Southern Cross constellation. The two main stars of the system can be seen in a good small telescope; they’re similar to the sun and have the designation A and B.
However, Proxima isn’t even in the same field, it’s a good two degrees further south and, so dim, you need a large amateur telescope to see it from the suburbs.
One-tenth of a light year closer to us than the other two, it’s classed as a red dwarf star with very low luminosity. It’s also a ‘‘flare star’’, meaning it can increase its brightness suddenly and unexpectedly. Studies have not indicated any planets orbiting it. Though dwarfed in size and brightness, it will far outlive the other two stars, reaching an age 300 times the current age of the universe.