Water on an Alien Planet

October 2019 headlines proclaimed that for the first time ever, the Hubble Space Telescope discovered water vapor in the atmosphere of an earth-size planet orbiting in the habitable zone of a distant star.

K2-18b appears to be the only planet yet found outside our solar system with the right temperature to hold water in all its states.

Earth size is perhaps a misleading term since this “super earth,” with the name K2-18b, has eight times earth’s mass. Still, it appeared to be a first—the only planet yet found outside our solar system with the right temperature range to hold water in all its states. To secular scientists, the discovery seems like a step closer to finding habitable worlds beyond earth.

The difficulty in finding planets with the right temperature range to support a water cycle emphasizes just how special earth is. The precisely balanced conditions here are truly rare—probably unique. And water is just the beginning. It takes much more than liquid water to support life. God placed exuberant diversity throughout his creation, and the water on K2-18b is another example. But that doesn’t make it habitable.

In fact, right after the initial announcement, astronomers worldwide criticized the report, saying the planet was probably gaseous like Neptune with possibly no solid surface. Liquid water doesn’t equal habitability, and even if astronomers find a truly habitable planet someday, it doesn’t mean it is actually inhabited.

This article was taken from Answers magazine, January–February, 2020, 21.