Extraterrestrial life is life that may exist and originate outside the planet Earth, the only place in the universe currently known by humans to support life.
Its existence is currently purely hypothetical as there is yet no evidence of any planets that can support life, or actual extraterrestrial life that has been widely accepted by the scientific community.
Most scientists hold that if extraterrestrial life exists, its evolution would have occurred independently in different places in the universe.
An alternative hypothesis, held by a minority, is panspermia, which suggests that life in the universe could have stemmed from a smaller number of points of origin, and then spread across the universe, from habitable planet to habitable planet.
These two hypotheses are not mutually exclusive.
Astrobiology Astrobiology is the study of life in space, combining aspects of astronomy, biology and geology. It is focused primarily on the study of the origin, ... >
read more
Radio telescope A radio telescope is a form of radio receiver used in astronomy. In contrast to an "ordinary" telescope, which receives visible light, a radio ... >
read more
Planetary habitability Planetary habitability is the measure of an astronomical body's potential to develop and sustain life. It is generally assumed that any ... >
read more
Alpha Centauri Alpha Centauri (α Cen / α Centauri) is the brightest star system (a triple star system) in the southern constellation of Centaurus, and ... >
read more
Carl Sagan Dr Carl Edward Sagan (November 9, 1934 - December 20, 1996) was an American astronomer, astrobiologist and highly successful science popularizer. He ... >
read more
Ultimate fate of the universe The ultimate fate of the universe is a subject of study in the field of cosmology. Vying scientific theories predict whether the life of the universe ... >
read more
Impact crater An impact crater is a circular depression on a surface, usually referring to a planet, moon, asteroid, or other celestial body, caused by a collision ... >
read more
Multiverse A multiverse (or meta-universe) is the hypothetical set of multiple possible universes, including our universe, which comprise the absolute whole of ... >
read more
Extrasolar planet An extrasolar planet, or exoplanet, is a planet beyond the Solar System. As of 11 November 2006, 209 extrasolar planets have been discovered.
Known ... >
read more
Equatorial bulge An equatorial bulge is a planetological term which describes a bulge which a planet may have around its equator, distorting it into an oblate ... >
read more