Location

The orientation of an object to the surrounding space is referred to as spatial position , especially with regard to the horizontal or the plumb direction .

A complete specification also includes its direction and sometimes also the height .

The spatial position in the above horizon system is primarily determined by our equilibrium organ, but supported by the eye and the muscular sense . However, the sense of balance can be disturbed by unusual movements or postures (e.g. vertigo ). It is more reliable with a spirit level or the artificial horizon on an airplane . Precise measurements use special plumbing sensors or vials for leveling .

Rotational movements are controlled through the semicircular canals in the inner ear, when flying instruments with the turn pointer . North-related directions are mainly measured with a magnetic compass ; for exact geodetic measurements see below.

Tilt

The angle between the base (or the longitudinal axis ) of a body and the local horizon is called the slope or inclination . In aircraft , this angle (rotation around the transverse axis) is called pitching , while the angle of rotation around the longitudinal axis is called roll .

In the case of machine axes , one speaks of axis inclination , in the case of non-horizontal terrain of incline or slope inclination , in the case of changing heights of traffic routes of the gradient . In geology, the spatial position of rock strata and fissures is determined by measuring the angle of fall and strike . In geotechnics , these elements are represented on the so-called layer sphere , which in mathematics corresponds to a directional or unit sphere .

While in everyday life one relates the spatial position to the horizontal or to a flat surface of the earth , in astronomy separate definitions are necessary. The position of a satellite orbit is related to the plane of the earth's equator and is referred to as orbital inclination.

direction

In addition to the inclination of an object or an axis to the horizon, the spatial position also includes its orientation relative to the north , especially when the object (or person) is moving. This direction is commonly referred to as the compass direction , in science and technology mostly as the azimuth .

In navigation one speaks of course , which can refer to geographic or magnetic north . In English it is called Course or track ( course over ground ) or as Heading ( heading refers).

Geodesy and Geography

In the earth sciences - depending on the task - several coordinate systems are in use:

the horizon system (see above) for measurements on the earth's surface with theodolite and similar instruments
the orthometric height system (level surfaces of the earth's gravity field ) for height measurement ( leveling, etc.)
latitude and longitude for location information on the mean earth ellipsoid - v. a. for geography , GPS surveying and navigation
- the UTM coordinate system for cartography
the geodetic date on the reference ellipsoid of the respective national survey and
- the Gauß-Krüger coordinate system as its special case
geocentric coordinates (mostly X, Y, Z ) with origin in the center of the earth .

Astronomy and space travel

In a weightless room there is no natural reference to a perpendicular direction . Therefore, the spatial position is determined here with regard to astronomically defined directions and planes:

when observing stars relative to the mean position of the earth's equator - in the astronomical coordinate system ( right ascension and declination )

in the case of earth satellites , rockets and near-earth space probes relative to the current earth equator - namely as the inclination of the orbit and as the length of the ascending node of the respective orbit plane

for control of rocket launches horizontally oriented gyro platforms

Stabilization of space probes through astronomically oriented platforms and star sensors oriented towards bright stars

For bodies of the solar system and more distant space probes, reference to the ecliptic (mean plane of the earth's orbit) and the line of intersection ( node length ) with it

for celestial bodies outside the solar system as galactic coordinates .

literature

J. Bennett et al .: Astronomy (chapter coordinates, space etc.). Pearson-Studienverlag, Munich-Boston-Harlow-Sydney-Madrid 2010
H. Simon: Instrument Aviation and Navigation , Part I. Hanns Reich Verlag, Munich 1961
K. John and R. Deutsch: The application of the layer sphere in geotechnics. Institute for Rock Mechanics and Tunnelba, Graz University of Technology, PDF; 495 kB ( Memento from November 1, 2013 in the Internet Archive )
R. Hengstenberg: Posture, locomotion and vision , biological cybernetics of flight, Max Planck Society 1994, online (PDF; 233 kB)