Communications satellite. Illustration of a satellite relaying signals between two ground stations on Earth against the backdrop of an aurora. Communications satellites relay telephone and television signals around the globe. Many are part of an international system called Intelsat, which links different countries. A typical communications satellite orbits with the same period as the rotation of the Earth. The satellite does not appear to move in the sky and is said to be geostationary. Aurorae are displays of light which occur at high latitudes. They are caused by energetic, charged particles from the Sun colliding with atoms in the Earth's atmosphere.