Wyzdom, the third of four planets orbiting Alpha Centauri A, an identical twin of Earth’s own sun and its nearest stellar neighbor, lies a “scant” 4.3 light years from Earth. Wyzdom’s night sky appears identical to Earth’s except that the constellation Cassiopeia contains an additional bright star, Earth’s sun.
Unlike Earth’s sun, however, Alpha Centauri A is but one star in a triple star system which contains a smaller K type star, called Alpha Centauri B, and a tiny M type star known as Proximo Centauri. Stars A and B orbit each other once every 80 years in a highly elliptic path, at a distance that varies between 35 and 11 astronomical units. Since star B lies as far from A as the planet Saturn lies from Earth’s sun, its radiation comprises less than six percent of the total falling on Wyzdom and therefore has little effect on the planet’s surface temperature.
The companion star is the second brightest object in Wyzdom’s heavens and, visible both day and night, appears as a brilliant dot some 1500 times brighter than Earth’s moon. During half of a Wyzdom year, the companion star appears in the day sky, while during the other half, it shines in the night sky. On those nights, it obliterates all but the brightest stars, creating a continuous twilight. Wyzdomites call these months “am” months, and the months when the companion star rises during the day they call “nocht” months. As each 80-year period passes, the am and nocht months shift from winter to summer, and back again, creating a complex pattern of seasonal variations that profoundly influences the native life forms.
The third star of the Alpha Centauri system, Proximo, orbits the other two at a distance of about 11 thousand astronomical units, more than 270 times the distance that the planet Pluto orbits Earth’s sun. Though invisible to the naked eye from Earth, Proximo appears in Wyzdom’s sky as a moderately bright star of magnitude 3.6.
More than one planet in the Alpha Centauri system possesses life, though the second holds greater interest for scientists than for potential pioneers. Graves’s Planet occupies the second orbit of the companion star, Alpha Centauri B. Its life is chlorine/silicone based rather than oxygen/carbon based. It is quite primitive in comparison with the sophistication of life on Wyzdom. Yet the discovery of life on Graves’s Planet during the second expedition to Alpha Centauri excited scientists almost as much as the discovery of life on Wyzdom, for it proved that elements other than carbon, oxygen and nitrogen could form the basis of life and greatly increased the probability of encountering other intelligent life in the galaxy.