Short answers, pulled from the story.
The orbital inclination measures zero degrees when a satellite hovers directly above the Earth's Equator. This alignment means the path traces the exact same circle as the planet's widest point.
An inclination of 63.4° holds special significance because it results in zero apogee drift for highly elliptical paths. Engineers call this value the critical inclination to maintain stable coverage for systems like Arctic Communications.
Most exoplanets discovered through the radial-velocity method possess inclinations between 45° and 135° because the technique detects planets more easily when their orbits approach an edge-on configuration. An inclination of 90° marks an edge-on orbit parallel to our line of sight, while 0° indicates a face-on orbit where detection is difficult.
Peter Goldreich published a classic paper in 1966 regarding the evolution of the Moon's orbit. He examined how moons behave across different distances from their parent planets and identified a critical distance separating distinct behaviors.
Dwarf planets like Pluto exhibit inclinations to the ecliptic of 17°, while Eris displays an even steeper tilt at 44° relative to the same baseline. The large asteroid Pallas sits inclined at 34° to the ecliptic, contrasting sharply with the near-zero inclinations of major planets.