An orbit which is contained in the plane of reference (called non-inclined) has no nodes.

However, any direction can serve as the plane of reference, as long as it is clearly defined for everyone using that system.

In celestial mechanics, the plane of reference is the plane used to define orbital elements (positions).

On the plane of reference, a zero-point must be defined from which the angles of longitude are measured.

If a reference direction from one side of the plane of reference to the other is defined, the two nodes can be distinguished.

Common planes of reference include:

Engineers have traditionally used polished granite surface plates to establish a plane of reference, since they are relatively impervious and inflexible.

Because of the different physical laws in that sort of para-void and considering the alien plane of reference there, it seems completely commonplace to them.

An orbital node is one of the two points where an orbit crosses a plane of reference to which it is inclined.

The line of nodes is the intersection of the object's orbital plane with the plane of reference.

Although height is relative to a plane of reference, most measurements of height in the physical world are based upon a zero surface, known as sea level.

They sometimes seem to operate on two simultaneous planes of reference, in fact, and they pay children the great compliment of not dumbing everything down for them.

The two main orbital elements that are measured with respect to the plane of reference are the inclination and the longitude of the ascending node.

It is the angular distance of the orbital plane from the plane of reference (usually the primary's equator or the ecliptic), normally stated in degrees.

An argument of periapsis of 90 means that the orbiting body will reach periapsis at its northmost distance from the plane of reference.

Prior to Captain Meade's command, Great Lakes' water level readings were taken locally with temporary gauges; a uniform plane of reference had not been established.

Owing to the time-dilation effect of the present continuum, probably only a few days had passed for us; but on another plane of reference the time-rate would have remained stable.

The cubic volumes on the octagonal base, they rotate on a 45 degree plane of reference and diminish in volume towards the top of UOB Plaza One.

In order to determine the height of a mountain, one should do this from sea level (the plane of reference), but here the distances can be too great and the mountain may not be visible.

Normally the description requires no axial orientation indication if the profile is asymmetric and if it does exists, then axial orientation with respect to some suitable plane of reference is required.

The longitude of periapsis is a compound angle, with part of it being measured in the plane of reference and the rest being measured in the plane of the orbit.

If the plane of reference is the equator, these orbits are called equatorial; if the plane of reference is the ecliptic, they are called ecliptic.

An argument of periapsis of 0 means that the orbiting body will be at its closest approach to the central body at the same moment that it crosses the plane of reference from south to north.

If it is versor in nature, then the part affected by the radical involves the axis perpendicular to the plane of reference, and this is so, whether the radical involves the square root of minus one or not.

Specifically, ω is the angle between the orbit's periapsis (the point of closest approach to the central point) and the orbit's ascending node (the point where the body crosses the plane of reference from South to North).