An artificial satellite is a human-made object that is intentionally placed into orbit around a celestial body, such as the Earth or other planets. There are currently over 3,000 active satellites orbiting the Earth. Satellites have a variety of uses, including communication relay, weather forecasting, navigation, broadcasting, scientific research, and more. The size, altitude, and design of a satellite depend on its purpose. Some of the key components of a satellite include:

• Power source: Most satellites have solar panels to generate electricity. Batteries store some of this energy for times that the satellite is in the shadow of the Earth.

• Heat control system: Satellites are exposed to extremely high temperatures due to exposure to the Sun. There needs to be a way to reflect and reradiate heat. Electrical components of the satellite can also produce a lot of heat.

• Computer system: Satellites need computers to control how they operate and also to monitor things like altitude, orientation, and temperature.

• Communication system: All satellites need to be able to send and receive data to ground stations on Earth or to other satellites. Curved satellite dishes are used as antennae.

Satellites can be built to perform various tasks, including taking aerial photographs of Earth that help meteorologists predict the weather, taking pictures of astronomical bodies and distant galaxies, which helps scientists to better understand the cosmic system, and for communications around the world and for finding ones position, e.g. the Global Positioning System (GPS). The first artificial satellite was launched into space in 1957 by the Soviet Union, and it was called Sputnik 1.