A satellite is an object that goes around, or orbits, a larger object, such as a planet. While there are natural satellites, like the Moon, hundreds of man-made satellites also orbit the Earth.
What are the components of a satellite?
Communications antennae, radio receivers and transmitters enable the satellite to communicate with one or more ground stations, called command centers. Messages sent to the satellite from a ground station are "uplinked"; messages transmitted from the satellite to Earth are "downlinked."
Many satellites are battery-powered, taking advantage of the ultimate battery recharger, the sun. Silvery solar panels are prominent features on many satellites. Other satellites have fuel cells that convert chemical energy to electrical energy, while a few rely on nuclear energy. Small thrusters provide attitude, altitude, and propulsion control to modify and stabilize the satellite's position in space. Energy is also required to provide climate control onboard for delicate instruments (and sometimes for people).
Specialized systems accomplish the tasks assigned to the satellite. These often include sensors capable of photographing a range of wave lengths. Telecommunications satellites require no optics, while environmental satellites do. Environmental satellites transmit data as numbers to a computer on Earth which translates this digital data into images.
While some of the images on the computer screen look like photographs, some don't. Bright colors (false colors) are often added to enhance the contrast to make details stand out or to allow us to see what was recorded in the infrared wavelength, beyond our visual range. False colors do not correspond to the colors we normally see. For example, a field of wheat might look pink; clear water may appear black.