Stars are brilliant beacons of light shining through the vast cosmic darkness. But just how brilliant they are, and how far they shine across the darkness, varies by a huge amount. In our Milky Way galaxy, for example, the most brilliant stars are several billion times brighter than the faintest ones.
What the faint ones lack in power, though, they make up for with numbers -- they account for most of the galaxy's stars, and most of our stellar neighbors, including the closest one of all. Yet not a single one of them is bright enough to see from Earth with the eye alone.
These stars are known as red dwarfs. Their surfaces are so cool that they shine reddish-orange, like dull cosmic embers.
They range from about half down to less than one-tenth the mass of the Sun. With such little material, the nuclear furnaces in their cores chug along at a leisurely rate, so they produce little energy. In fact, those at the low end of the scale are so feeble that it takes them a year to emit as much energy as the Sun produces in just an hour.
These stars are quite turbulent, though. A red dwarf's surface layers bubble like a boiling tea kettle. All of that motion generates powerful magnetic "storms": dark "starspots" that can cover close to half of the star's surface, and powerful explosions that shower space with X-rays.
Yet red dwarfs should be good targets to search for planets. We'll explain why tomorrow.
Script by Damond Benningfield, Copyright 2011
For more skywatching tips, astronomy news, and much more, read StarDate magazine.