A satellite’s altitude starts at the surface
A building’s height starts at the ground, not Earth’s centre. Satellite altitude works the same way. To measure from Earth’s centre, add the length from centre to surface.
Work it out, one step at a time
Choose the two connected lengths
R = 6,371 km; h = 35,786 km
This teaching example uses a mean spherical Earth and a representative geostationary altitude.
Add them
6,371 + 35,786 = 42,157 km
The result starts at the centre. It is not the altitude or the distance around the orbit.
Words made simple
- Geostationary
- An equatorial circular orbit that matches Earth’s rotation, so the satellite appears fixed from the ground.
Think about it: A satellite is 500 km above the surface. What is its distance from the model Earth’s centre?
6,371 + 500 = 6,871 km. Marking the starting point prevents mixing the two distances.
Where the numbers come from: NASA JPL · ESA. The illustration and worked model are made for this lesson; assumptions are stated above.
Build a scale modelChoose two references and change the model size.
Build a scale model of any two lengths
Choose from all 71 Macro and 54 Micro references, or enter your own length. Set B’s model length and see A change on the same fixed metre ruler. The bars represent the stated lengths, including their different measurement definitions.
- Length ratio A / B
- Model length B
- Calculated model length A
A · Geostationary orbit
3.579e+7 m
Approximate geostationary altitude above Earth’s equator, 35,786 km.
Source claim checked
Altitude above the surface, not orbital radius from Earth’s centre.
Definition and evidence reviewOriginal sourceB · Earth circumference
4.008e+7 m
Approximate equatorial circumference, 40,075 km.
Source claim checked
Equatorial, not a meridian circumference; the mean-radius sphere has a different circumference.
Definition and evidence reviewOriginal sourcemodel A = (A / B) × model B
This calculator uses the existing journey comparison inputs. Review-pending or conceptual entries remain illustrative inputs here; the public reviewed dataset keeps their numeric values withheld. Radius, height, diameter and experimental bound keep their individual definitions.
Altitude and orbital radius
Adding the 35,786 km altitude to NASA's 6,378.137 km equatorial Earth radius gives about 42,164 km from Earth's centre. The orbit's full path is larger again: altitude, radius and circumference label different segments.
Stationary in the sky, moving in space
ESA describes a geostationary satellite as matching Earth's rotation while orbiting above the equator in the same direction. It remains over one longitude rather than hovering without motion. Ground-vehicle times serve as mathematical length comparisons; reaching orbit requires spacecraft and orbital mechanics.
Closest ScaleTrip references
Page distance: 35,786 km
- Geostationary orbitReference measurement: Altitude · 35,786 km
Ratio (page distance ÷ reference): ≈ 1×The altitude where a satellite matches Earth's rotation.
- Earth circumferenceReference measurement: Circumference · 40,075 km
Ratio (page distance ÷ reference): ≈ 0.89×One complete journey around Earth's equator.
- Earth diameterReference measurement: Diameter · 12,742 km
Ratio (page distance ÷ reference): ≈ 2.81×The distance through Earth's centre from one side to the other.
Sources for these values
- European Space Agency — Types of orbits — geostationary altitude of 35,786 km above the equator · source verified 2026-10-08
- NASA NSSDC — Earth Fact Sheet — equatorial radius 6,378.137 km, polar radius 6,356.752 km; diameter and orbital-radius comparisons derived from these · calculation verified from source value 2026-10-08