Key relationship
r=[GM(T/2π)²]^(1/3); geostationary T=86164.0905 s.
Physics · Class 11
Match a sidereal rotation
A geostationary satellite remains above one equatorial longitude only when its orbit is circular, equatorial, prograde and has the Earth’s sidereal rotation period. Changing the period produces longitude drift.
Open the interactive experiment →Match a sidereal rotation
புவிநிலை செயற்கைக்கோள் பூமத்தியரேகைத் தளத்தில் புவியின் சுழற்சியுடன் சம சுற்றுக்காலத்தில் அதே திசையில் சுற்ற வேண்டும்.
Key notes, relationships and model limits
Remember
A geostationary satellite remains above one equatorial longitude only when its orbit is circular, equatorial, prograde and has the Earth’s sidereal rotation period. Changing the period produces longitude drift.
Common trap
A 24-hour inclined satellite is not fixed above one point on Earth.
Model limits
Circular prograde equatorial orbit. Matching the sidereal period alone does not make inclined or eccentric orbits geostationary. Animation time represents hours when displaying drift.
What you will learn
Compute synchronous altitude and state every geostationary condition.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
For T=86164.0905 s, r≈4.216×10⁷ m and altitude≈3.579×10⁷ m. A 24-hour solar day gives a small longitude drift.
Why this matters
The model connects match a sidereal rotation with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
Which period produces geostationary motion?
- Exactly 24 hours, a solar day
- One sidereal day, about 23 h 56 min
- Half a sidereal day
Read the explanation
Earth completes a rotation relative to distant stars in 86164.0905 s.
Course connection: Class XI Chapter 7. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.