Changes

'''Extraterrestrial life''' is [[Life science|life]], whether demonstrated, hypothesized, or merely imagined, that did not obviously originate on the [[earth]]. It has been a staple of [[science fiction]] since the [[Edward VII|Edwardian]] era, but has also lately become the subject of intense speculation, scientific debate, and even theological debate.

'''Extraterrestrial life''' is [[Life science|life]], whether demonstrated, hypothesized, or merely imagined, that did not obviously originate on the [[earth]]. It has been a staple of [[science fiction]] since the [[Edward VII|Edwardian]] era, and has more recently become the subject of scientific debate and even theological debate.

The term ''life'' is here used in its usual manner to connote living things, regardless of complexity or condition of sentience.  However, in [[science fiction]] especially, extraterrestrial life may take unconventional form, such as non-carbon-based life forms or even disembodied intelligence.

The term ''life'' is here used in its usual manner to connote living things, regardless of complexity or condition of sentience.  However, in [[science fiction]] especially, extraterrestrial life may take unconventional form, such as non-carbon-based life forms or even disembodied intelligence.

Vigorous scientific research on the subject is fairly limited, and has focused on both the "micro" and "macro" aspects of the problem:

Vigorous scientific research on the subject is fairly limited, and has focused on both the "micro" and "macro" aspects of the problem:

# The [[exogenesis]], nature, survival, and movement of primitive life forms, including the hazard that such microbes might pose to [[astronaut]]s or to the earth itself.

# The genesis, nature, survival, and movement of primitive life forms, including the hazard that such microbes might pose to [[astronaut]]s or to the earth itself.

# The possibility of prior or future detection, contact, trade, or war with an extraterrestrial [[civilization]].

# The possibility of prior or future detection, contact, trade, or war with an extraterrestrial [[civilization]].