One-word substitution (space orbits near Earth): Identify the correct term for a fixed position orbit relative to the Earth, where a satellite appears motionless over a single longitude. Context: Differentiate from geo-synchronous (same period but not fixed point), geo-centric (Earth-centered generally), and other geologic terms. Instruction: Choose the most accurate single-word substitute.

Given data

• Description: a fixed orbit relative to Earth (satellite appears stationary in the sky).
• Nearby technical terms: geo-synchronous, geo-centric, geological.

Concept / Approach
A geo-stationary orbit is a circular, equatorial orbit with the same angular velocity as Earth's rotation, so the satellite appears fixed over one longitude.

Elimination reasoning
Geo-stationary — fixed over a point on the equator; correct. ✅Geo-synchronous — matches Earth's period but may be inclined/eccentric, thus not fixed in the sky. ❌Geo-centric — simply Earth-centered; includes many orbits. ❌Geological — relating to Earth's physical structure; not orbital mechanics. ❌

Example
Most communications satellites use geo-stationary orbits to maintain constant ground coverage.

Final Answer
Geo-stationary