Since its discovery by astronomers in 2015, the exoplanet k2-18b has elicited much excitement. Swirling around a red-dwarf star about 110 light-years away from Earth, the distant world sits in a so-called Goldilocks zone—not close enough to its host star to be too hot and not far enough away to be too cold—that could allow liquid water to flow across its surface. That is a crucial condition for life as we know it.

Source: The Economist