If a satellite has the orbit of 35786 km above Earth’s surface, the satellite will be in motion at the same speed as the Earth’s rotational rate. As a result, the satellite will appear practically motionless when observed from the surface. Many communication satellites reside in this orbit, and a satellite dish receiving signals from the satellite does not have to track the satellite.
Flat-Earthers often take the fact that satellites are in motion and most satellite dishes have a fixed direction as ‘proof’ the dishes cannot be pointing to satellites. They are wrong.
The lower the altitude of the orbit of a satellite, the higher its orbital speed. And conversely, the higher the orbit, the lower the orbital speed. From the relation, we can determine the orbital altitude where the angular speed matches that of the rotational rate of the Earth. The altitude is 35786 km above the Earth’s surface.
This orbit is called geostationary orbit. Any satellite placed in this orbit will have a fixed position relative to the surface of the Earth, as long as the satellite is above the equator and moves in the same direction as Earth’s rotation.
Because a geostationary satellite appears motionless relative to Earth’s surface, a satellite dish can be directed to a fixed direction and does not have to continuously track the satellite.
A geostationary satellite has to orbit above the equator. As a result, a satellite dish in the northern hemisphere needs to be pointed towards the south. And conversely, a satellite dish in the southern hemisphere needs to be pointed toward the north.
- Geostationary orbit – Wikipedia