The field of exobiology is the study of which topic?

Exobiology is a branch of biology that searches for the existence of living organisms and extraterrestrial environments outside of the Earth's atmosphere. Several researchers at NASA (National Aeronautics and Space Administration) and other space agencies focus on the field of exobiology. In part, they seek to confirm the possibility of life beyond Earth, but also to understand the origin, evolution, and distribution of life in the universe.

Exobiology incorporates several areas of research. One involves studying the planetary conditions required to support life, for example, what makes a planet habitable. They also explore the potential of life existing in non-oxygenated conditions.

Another area of research focuses on the early evolution of life on Earth. To understand life on other planets, scientists must understand our own. By studying life on Earth, scientists can better understand the early conditions of our planet and how life systems began to thrive. By applying this to other planets, scientists can determine whether they show similar signs of early evolution.

In the 21st century, exobiology is more commonly called astrobiology, deriving from the Greek words, 'astron' (star), 'bios' (life) and 'logia' (study). Exobiology derived from the Greek word for 'external'. Russian astronomer Gavriil Tikhov (1875-1960) introduced the term astrobiology, suggesting it implied a much broader study of the subject.