Atoms can link up to form molecules, including organic molecules and biological processes, in interstellar space as well as on planets. Is it possible that life began not only prior to Earth, but not on a planet at all? Image credit: Jenny Mottar.

Will Scientists Ever Discover Life Without A Home Planet?

The origin of life on Earth may have nothing to do with Earth at all.

“An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide.” -Alexei A. Sharov & Richard Gordon

By discovering the properties of the other worlds in our Solar System, it became clear that Earth was unique. Only we had liquid water on the surface; only we had large, complex, multicellular life whose evidence could be seen from orbit; only we had copious amounts of atmospheric oxygen. Other worlds may have subsurface oceans or past evidence for liquid water, with perhaps single-celled or prior life on it. Sure, other solar systems may have Earth-like worlds, with similar enough conditions that life arose there. But not only is an Earth-like world not necessarily required for life to exist, recent evidence shows us that having a world at all might not be needed. It may be possible to have life in the depths of interstellar space itself.