Alpha Centauri

Alpha Centauri is a star system that appears in the narrative as part of the evidence that Astrophage has infected multiple stars beyond Earth's sun, confirming the interstellar scale of the threat and shaping the Hail Mary mission's destination.

Role in the Astrophage Infection Map

When Eva Stratt presents Ryland Grace with the data that led to the Hail Mary Project, she shows him luminosity readings from amateur astronomers all over the world. The page has columns of numbers with column titles including "Alpha Centauri," "Sirius," "Luyten 726-8," and other stars in the local cluster. Stratt explains that professional astronomers do not study local stars—they look at faraway things—so it is the amateurs who log data on local stuff, some with tens of thousands of dollars' worth of equipment. The data, normalized across thousands of amateur-generated data sets and corrected for known weather and visibility conditions using supercomputers, reveals that Earth's sun is not the only star getting dimmer. Grace immediately understands the implication: Astrophage can travel at 0.92 times the speed of light, and if it can go dormant and stay alive long enough, it could infect nearby stars. He compares it to mold spores spreading from star to star. The NSA back-calculated propagation models for how Astrophage could get around in the galaxy, and the data shows that local stars have been dimming for decades, with the rate of dimming increasing exponentially—just like what is happening with the sun. The trail of infection, adjusted for the speed of light and distances of the stars, shows that Earth's sun was infected by a star called WISE 0855–0714, which was infected by Sirius, which was infected by Epsilon Eridani. From there, the trail goes cold. Alpha Centauri appears in this data as one of the stars whose dimming has been observed, confirming that the Astrophage infestation is not limited to Earth's solar system but is a local interstellar phenomenon.

Significance for the Mission

The evidence that Alpha Centauri and other nearby stars are also dimming due to Astrophage infection underscores the urgency of the Hail Mary mission. The data shows that every star eventually infects all of its neighbors within a maximum range of just under eight light-years, which is the distance Astrophage can coast while dormant. Most stars have another star within eight light-years, so that is as far as Astrophage had to evolve to travel while sporing. The stars only get to about ten percent dimmer before they stop dimming, but if Earth's sun dims by ten percent, all life on Earth would die. This interstellar context makes Tau Ceti—the one star in the infected cluster that remains unaffected—the critical destination for finding a solution. Alpha Centauri's inclusion in the infection map demonstrates that the problem is not isolated to Earth's sun but is a regional galactic crisis, and that understanding why Tau Ceti is immune could provide the key to saving not just Earth but potentially other star systems as well.