Echoes of Home
23 Mar 2016Birdnose
Discovery, in the Arcturus system, might be the closest thing to my homeworld that I've seen in human space.Arcturus itself is an orange giant, a far older star than Sol. It has slightly more mass than Sol, but 25 times the radius and 170 times the brightness. This pushes the habitable zone outwards, and so we have Discovery, an extremely Earth-like planet that's in a very un-Earth-like 11 AU orbit.
Discovery was one of the early human colonies; it sits a little over 36 ly from Sol, only two jumps in my Type-6, but a much more daunting distance when it was first settled. Early colonists must have been thrilled by how familiar it seemed -- gravity almost identical to Earth's, an oxygen-bearing atmosphere, and a reasonably comfortable surface temperature. It would be interesting to see how the colonists have adapted to the longer day -- nearly 34 standard hours -- and the much slower seasonal changes. While the slow, 7-plus-Earth-year seasonal changes seem normal to me, they must seem interminable to a race that evolved on a planet that whips tightly around a young star.
Discovery's eventual fate will be the same as my homeworld's. At this point Arcturus has probably exhausted the hydrogen in its core, and is burning it in shells closer to the surface at an ever-increasing rate. It will get brighter and brighter until the core gets hot and dense enough to begin helium fusion. Billions of years' worth of accumulated helium will ignite all at once in an explosion that will be invisible from the surface, but will destroy the star's core. The end will come quickly after that, in astronomical terms; Arcturus will rapidly become darker and cooler as it begins to collapse into a white dwarf, and Discovery will be a dark, frozen world within a few thousand years. This process could start tomorrow, or it could start a hundred million years from now; we can't see what's going on in the core.
My solar system will not die in my lifetime, but unlike Sol's, it may die soon enough that it's still inhabited by people who are recognizably my species. That looming cloud is, I think, why we've colonized our region of space so enthusiastically.