Point: Any geostationay satellite covers slightly less than half. (So you only need three to cover the earth.)
Synthesis of answer:
- So you hire a shuttle place one over Newcastle with orbit period of 24 hours.
- However, it has to orbit the earth. To do that, it must orbit the centre of Earth's mass, i.e. centre of Earth.
- From the satellite (little diagram,) chop open the earth straight through the middle. We see that the orbit will lie on this plane.
- The satellite moves along, and must pass to the Taiwanese (;p) side of the equator as it orbits. Hence it cannot stay over Newcastle.
(In fact it inscribes a figure 8 because most satellites are on elliptic orbits, and move faster whenever they are closer and vice versa. Compared to the earth's speed of rotation, this makes the satellite drift forward a bit when they are close, and lag behind when they are far. To 'prove' this fast/slow business, use conservation of energy: GPE and KE.)