LIFE IN UNIVERSE!!!!!!!!!!!!!!

英文：
life in universe=Extraterrestrial life
Extraterrestrial life is defined as life which does not originate from planet Earth. The existence of life outside the planet is theoretical and all assertions of such life remain disputed.
Hypotheses regarding the origin(s) of extraterrestrial life, if it exists, are as follows: one proposes that it may have emerged, independently, from different places in the universe. An alternative hypothesis is panspermia or exogenesis, which holds that life emerges from one location, then spreads between habitable planets. These two hypotheses are not mutually exclusive. The study and theorization of extraterrestrial life is known as astrobiology, exobiology or xenobiology. Speculated forms of extraterrestrial life range from life with the simplicity of bacteria to sapient or sentient beings.
Suggested locations which might have once developed, or presently continue to host life similar to our own, include the planets Venus and Mars, moons of Jupiter and Saturn (e.g. Europa, Enceladus and Titan) and Gliese 581 c and d, recently discovered to be near Earth-mass extrasolar planets apparently located in their star's habitable zone, and with the potential to have liquid water.
To date, no credible evidence of extraterrestrial life has been discovered which has been generally accepted by the mainstream scientific community. All other proposals, including beliefs that some UFOs are of extraterrestrial origin (see extraterrestrial hypothesis) and claims of alien abduction, are considered hypothetical by most scientists. In 2006, New Scientist published a list of ten controversial pieces of evidence that extraterrestrial life exists, but scientists do not consider them credible since no direct observational evidence has been encountered.

2009-09-26 23:09:39 補充：
中文：

外星生命一般指存在於地球以外的生命體。它們尚沒有被目前地球上的生命所觀測到，倒是許多虛構作品中時常有它們的出現。它們與外星人時常被作為人類文藝節目討論或展示的對象。當然始終有人相信有外星人存在。但是目前沒有確鑿的證據來證實這一點。

2009-09-26 23:09:45 補充：
人們在火星隕石中找到了微生物化石，再加上大量的外星人造訪地球的報道，科幻小說、電影的充斥，使得外星生命的傳聞繪聲繪影。然而這些證據實在不足以證明外星生命的存在，長久以來，科學界一直對存在飛碟等外星生命的證據持嘲笑態度。1947年美國羅斯威爾飛碟墜毀事件曾引起軒然大波，後來美國國防部聲稱這不是真的。

地外文明指宇宙中除地球上的文明以外的文明，常與外星生命相聯繫。有人猜測地外文明可能比地球上的文明發達。