Astrobiology is the study of the origin, evolution, distribution, and future of life on Earth and in the universe. It encompasses research in, among others, the fields of astronomy, chemistry, evolutionary biology, field and population biology, geology, microbiology, molecular biology, oceanography, paleontology, and planetary science. Astrobiology includes investigations of the geologic and fossil record to understand the conditions of the early Earth when life arose. Its scope also includes research of contemporary locations on Earth that might be similar to early earth and to environments elsewhere in the Solar System (such as on Mars, Europa, and Titan), which may be, or have been in the past, suitable for life. Astrobiology is also about understanding the characteristics of life, which requires investigations into extreme natural environments on Earth and, eventually, elsewhere.