A satellite is an object that orbits, or circles around, a larger object in space. The Moon is Earth's natural satellite, held in orbit by Earth's gravity. It takes about 27 days for the Moon to complete one trip around our planet.

But when most people today say “satellite,” they mean an artificial satellite: a machine that humans have launched into space to orbit Earth or another celestial body. These manufactured satellites do all kinds of important work. Weather satellites watch clouds and storms forming, helping meteorologists predict if you'll need an umbrella tomorrow. Communication satellites relay television signals, phone calls, and internet data across oceans. GPS satellites help drivers navigate unfamiliar roads and help ships find their way across vast oceans.

The first artificial satellite, Sputnik 1, was launched by the Soviet Union in 1957. It was about the size of a beach ball and did nothing but send radio beeps back to Earth, but it marked the beginning of the Space Age. Today, thousands of satellites orbit our planet, and we depend on them for weather forecasting, global communications, scientific research, and navigation.

The word can also describe something that depends on or revolves around something more important, like a satellite office of a company located away from the main headquarters.