The 45 planets most likely to host alien life, according to astronomers

'Project Hail Mary' may be fiction, but this list could still come in handy. An artist's impression of a theoretical planet orbiting a redder star, which could cause microbes and plants on the planet's surface to reflect very different colors from Earth's green forests. Breakthroughs, discoveries, and DIY tips sent six days a week. Life on Earth is a precious thing, especially given what astronomers know about the visible universe. Although researchers have so far identified over 6,000 exoplanets beyond our solar system, only a handful of them be suitable for human visitors.