Last week, the human race met its very first Earth-like planet orbiting a Sun-like star in the habitable zone. Kepler-452b’s discovery was met with resounding excitement, but the news was bittersweet. Because life on this distant world — if it exists at all — could be facing imminent extinction.
Earth’s new cousin has spent the last spent 6 billion-ish years in the habitable zone, but its aging, brightening star could’ve already kickstarted a runaway greenhouse event, spelling the beginning of the end for complex life. In a billion years, a similar process will transform the Earth into a miserable wasteland.
Aging is a natural step in planetary evolution, and it’s one that 452b might help us understand. To speculate about what’s going down on this distant world, scientists rely on what we know about how our own biosphere will die.