Satellites, Science of

Many of our modern global communication systems depend on satellite technology. In the most general sense, a satellite is any object that orbits another object in space. Hence the Earth is a satellite of the sun, and the moon is a satellite of the Earth. However, when thinking about satellites today, most human-made satellites in orbit around the Earth come to mind. These are critical to any number of modern technological systems. They enable communication across continents but also monitor the Earth's weather, look for evidence of climate change, help us create accurate maps, and track everything from the movements of arms and armies to the delivery of packages.

Any object in orbit is actually a satellite, from a dropped wrench used by an astronaut to ...