An artificial satellite is an object intentionally placed into orbit around a celestial body, such as the Earth, Sun, or another planet, using rockets. There are currently over 3,000 active satellites orbiting the Earth, and their size, altitude, and design depend on their purpose. Some common uses of artificial satellites include communication relay, weather forecasting, navigation, broadcasting, scientific research, and military support. Satellites can also be used to study the universe, monitor crops and other resources, and support space exploration.

Artificial satellites have four main parts: a power system, a way to control its attitude, an antenna to transmit and receive information, and a payload to collect information. Satellites also need a heat control system to reflect and reradiate heat, as well as a computer system to control how they operate and monitor things like altitude, orientation, and temperature. All satellites need to be able to send and receive data to ground stations on Earth or to other satellites, and curved satellite dishes are used as antennae.

The largest artificial satellite ever is the International Space Station, which is as big as a large five-bedroom house, but including solar panels, it is as large as a rugby field. Satellites can vary in size, with some cube satellites as small as 10 cm and some communication satellites about 7 m long with solar panels that extend another 50 m.

In summary, artificial satellites are human-made objects intentionally placed into orbit around a celestial body for various purposes, such as communication, weather forecasting, navigation, and scientific research. They have four main parts and require a heat control system, a computer system, and a communication system to operate.