Satellite, Artificial, a man-made object that orbits the earth, the moon, the sun, or any other celestial body. On October 4, 1957, the Soviet Union's Sputnik I became the first man-made object to be placed in orbitan event that ushered in the space age.

The advent of the space age had a profound influence on education in the United States. The science content of high school curricula was modernized, and advanced study in engineering and the sciences received new emphasis. Later, there was a widening exploration into the methods and principles of teaching, to enable students to cope with the rapidly changing and expanding technological aspects of society. Politically, the ability to orbit ever heavier and more complex satellites immediately became a matter of prestige among nations, particularly the United States and the Soviet Union. The concepts of international law were extended to space, and many political questions were raised. Some of these questions, such as the banning of nuclear weapons in space, were settled, but other issues, such as the development of weapons to destroy satellites in space, remain unresolved.

Satellites have important applications in communications and meteorology. Satellites are also important in the study of some of the most challenging problems of pure science, such as the origin of the earth and, indeed, of the whole universe.

The developments of space science have also provided society with direct benefits in the form of what has been called technological falloutthat is, inventions and processes that were originally developed for the space program (or in an unsuccessful attempt to solve a problem for the space program) and later became useful in other applications. For example, metallized plastic film developed for an early artificial satellite called Echo later found use as a material for camping equipment, food packaging, and winter clothing. One unique application is as a lightweight emergency blanket that can protect a person against freezing temperatures, yet when folded is small enough to fit in a shirt pocket.