You are Here: Home >< Physics

# geostationary orbits watch

1. Why must a satelitte stay above the equator to remain in geostationary orbit?

any help greatly appreciated!

Im on Salters Horner's syllabus, doesnt seem to have this in the textbook but was on last years exam
2. love wikipedia...

Geostationary orbits can be achieved only very close to the ring 35,786 km (22,236 mi) directly above the equator. This equates to an orbital velocity of 3.07 km/s (1.91 mi/s) or a period of 1436.06 minutes which equates to almost exactly one earth day or 23.934461223 hours. This makes sense considering that the satellite must be locked to the earth's rotational period in order to have a stationary footprint. This can be calculated and verified here: [1]. In practice this means that all geostationary satellites have to exist on this ring, which poses problems for satellites that will be decommissioned at the end of their service life (e.g. when they run out of thruster fuel). Such satellites will either continue to be used in inclined orbits (where the orbital track appears to follow a figure-of-eight loop centered on the equator) or be raised to a "graveyard" disposal orbit.
3. lol sorry, still confused :s thanks though
4. The reason that they need to stay above the equator, is that, if they did any other sort of circuit, then they would appear to oscillate either side. Look at the equator, and imagine it tolted a few degrees, it would still pass over it, but as the ground moved underneath it, it's orbit would take it over different areas. In order to stay above any other place on earth would require the satellite to take a path that didn't bisect the earth, meaning that the forces wouldn't balance.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 7, 2008
Today on TSR

### University open days

• Southampton Solent University
Sun, 18 Nov '18
Wed, 21 Nov '18
• Buckinghamshire New University