Concept
Zenith
The point directly overhead.
The point on the celestial sphere directly above the observer.
Overview
The point on the celestial sphere directly above the observer.
See also
Nadir
The point directly below your feet.
Perihelion
The closest point in an orbit to the Sun.
Aphelion
The farthest point in an orbit from the Sun.
Perigee
The closest point in an Earth-centred orbit.
Apogee
The farthest point in an Earth-centred orbit.
Event Horizon
The point of no return around a black hole.