As our Sun gets older, brighter, and bigger over the next several billion years, it will expand into a red giant so large that its heat could melt ice on the surface of Europa and other moons of Jupiter, as well as those around Saturn. Liquid water flowing freely would not only be a boon for would-be space explorers, but it could provide a stable environment ripe for fostering life. The bad news is Earth will be burnt to a crisp. It may even get engulfed by the fiery wall of the expanding star, along with Mercury and Venus, so anyone that remains on Earth probably won’t live to see that day. For right now, however, humans who study planets orbiting other stars stand to benefit from the grim future prospects of our solar system’s innermost planets. A new model of the evolution of stellar systems’ habitable zones, based on what’s expected for our own solar system, could help observers today better evaluate which exoplanets could harbor life. Using their new model, researchers at Cornell University’s Carl Sagan Institute in Ithaca, N.Y., have found that the habitable zones around stars that have aged into red giants may exist for perhaps billions of years after the star’s expansion. https://eos.org/articles/aging-stars-make-new-habitable-zones
