Four point two light-years away, a planet slightly larger than Earth circles a red dwarf star, and scientists believe liquid water might flow across its surface right now. We call this world Proxima Centauri b, and it represents just the beginning of humanity's greatest discovery - planets beyond our solar system where life could actually exist.
Tonight, we journey to worlds where underground oceans hide beneath ice sheets, where one side burns in eternal daylight while the other freezes in permanent darkness, and where the very air might shimmer with the chemistry of life itself. From planets with diamond rain to worlds where a single day lasts longer than our entire year, each destination brings us closer to answering the ultimate question.
