Like all stars, our Sun will eventually die. In around five billion years its supply of hydrogen will run out, and it will become a red giant, expanding to well over thirty times its current size. As it grows, the Sun will engulf all the inner planets, making them far too hot for life to survive.
There’s nothing we can do to prevent this cataclysm. Yet according to scientists who study the far future, including Yale University astronomer Gregory Laughlin, the prospect for life is, oddly, rather bright. Given technological advances and the continuing evolution of our species, humans should be able to survive — in some form — long after Earth has ceased to exist.
But our distant descendants are going to have to do some planet-hopping. The first major cosmic crisis will strike in about 1.5 billion years. At that point, according to projections by environmental scientist Andrew J. Rushby at the University of East Anglia in England, the brightening sun will set off what might be termed “super-global” warming. Earth will be heated until the oceans boil.
By then, though, will we care? We already have the technology to establish bases on the moon and Mars. So a billion and a half years from now, we’ll likely have colonized the whole solar system — and perhaps other star systems in our Milky Way galaxy.
As the sun grows hotter, other planets will become more appealing. Just as Earth becomes too toasty to sustain life, Mars will reach a temperature that makes it habitable. Cornell University astronomer Lisa Kaltenegger has run models showing that the Red Planet could then stay pleasant for another 5 billion years.
About 7.5 billion years from now, the sun will exhaust its hydrogen fuel and switch to helium. That will cause it to balloon into an enormous red giant. Mars as well as Earth will be fried. On the other hand, the once icy moons of Jupiter and Saturn will have become tropical water worlds — prime real estate for human colonies. We could live there for a few hundred million years.
About 8 billion years from now, the flaring sun will make conditions intolerably hot all the way out past Pluto. “The exact dates depend on how much mass you estimate the sun will lose and how much planets will move,” Kaltenegger says. But the message is clear: Life will be impossible in our solar system.