Space Exploration
Extraterrestrial
The term 'extraterrestrial' refers to anything originating, existing, or occurring outside the Earth or its atmosphere. It is commonly associated with the concept of life beyond Earth, encompassing both microbial organisms and intelligent beings.
Galilean moons
The Galilean moons are the four largest satellites of Jupiter—Io, Europa, Ganymede, and Callisto—first observed by Galileo Galilei in January 1610. They exemplify diverse worlds, from Io’s extreme volcanism to Europa’s likely subsurface ocean, Ganymede’s intrinsic magnetic field, and Callisto’s ancient, crater-scarred surface.
NASA
The National Aeronautics and Space Administration (NASA) is the United States’ civilian space agency, established in 1958 to conduct aeronautics research and space exploration. Headquartered in Washington, D.C., NASA leads human and robotic missions, Earth and space science, and advanced aerospace technology programs in partnership with domestic and international collaborators.