Ross Andersen writes: In the Southern Hemisphere’s sky, there is a constellation, a centaur holding a spear, its legs raised in mid-gallop. The creature’s front hoof is marked by a star that has long hypnotized humanity, with its brightness, and more recently, its proximity.

Since the dawn of written culture, at least, humans have dreamt of star travel. As the nearest star system to Earth, Alpha Centauri is the most natural subject of these dreams. To a certain cast of mind, the star seems destined to figure prominently in our future.

In the four centuries since the Scientific Revolution, a series of increasingly powerful instruments has slowly brought Alpha Centauri into focus. In 1689, the Jesuit priest Jean Richaud fixed his telescope on a comet, as it was streaking through the stick-figure centaur. He was startled to find not one, but two stars twinkling in its hoof. In 1915, a third star was spotted, this one a small, red satellite of the system’s two central, sunlike stars.

To say that Alpha Centauri is the nearest star system to Earth is not to say that it’s near. A 25 trillion mile abyss separates us. Alpha Centauri’s light travels to Earth at the absurd rate of 186,000 miles per second, and still takes more than four years to arrive. [Continue reading…]