Introduction
Is there life in outer space? The fascination of intelligent life other than ourselves has led to many studies and theories. With recent discoveries about the universe, the idea of intelligent life has become even more intriguing. The implications of proving life exists on other planets and communicating with them could have an enormous impact to our society. The following discusses the possibilities of life on other planets by studying what sustains life on planet Earth, possible life within our solar system, the discovery and study of other life bearing planets, examines what criteria may sustain life in other stars systems, and current programs studying extraterrestrial life.
The properties of life on Earth
About 4.5 billion years ago, planet Earth was formed and experienced heavy bombardment by large asteroids and comets. Evidence shows life evolved on Earth around 3.85 billion years ago. “Chemical reactions in the oceans or through migration from Venus or Mars, living organisms quickly took hold. After the end of the heavy bombardment, the first organism, evolution rapidly diversified life on Earth” (Bennett, et al, 2007, p716).
The many different forms of life on Earth have three requirements; this gives us a guide for life elsewhere. The three requirements are; a source of nutrients from which to build living cells, energy source to fuel the activities of life, and liquid water. Nutrients and energy are available to some degree on almost every planet and moon. Many worlds are large enough to retain heat and provide energy, just about all the worlds have enough sunlight on their surfaces to provide energy, and nutrients in the form of organic molecules are found just about everywhere. The only requirement that is rare in our search for life in the universe is liquid water. (Bennett, et al, 2007, p718).
Extraterrestrial Life
While most alien life forms are the typical fictional green Marian characters, there are other more...