Axis inclination

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As axis tilt (also: axis tilt , Achsschiefe ), in a measuring instrument , the deviation of an axis of the horizontal or vertical respectively.
In astronomy , the angle between the axis of rotation of a celestial body and the normal of its orbital plane (orbit) is also referred to as axis inclination .

measuring technology

Axle inclination affects i. a. as a systematic error on the measurement and must therefore be considered and eliminated separately. The most common method for this is to attach an exact level or a digital sensor to the axis and read it during the measurement and then in the opposite position of the device.

The three axes of a theodolite: standing axis S, tilting axis K, sighting axis Z

For universal instruments and theodolites , the following axis inclinations are distinguished:

With the leveling device , only the axis inclination in the direction of the telescope is relevant and with modern instruments it is automatically compensated by a precise pendulum body ( automatic leveling ). In the case of channel lasers and other targeting instruments, it must be brought to zero by precise calibration , whereas in the case of fixed systems in mechanical engineering it is eliminated by adjustment in the bearings .


41,000 year cycle of the obliquity of the earth's axis

The axis inclination of a planet or moon is the angle between its axis of rotation and the normal on its orbital plane . You determined u. a. the seasons occurring on this celestial body . Axial inclinations between 90 ° and 270 ° characterize a retrograde (retrograde) rotation.

The earth currently has an axis inclination of 23 ° 26 ′ 21,406 ′ ′ (23.44 °), which also defines the polar circles and tropics . (For the cyclical change of this value see here .)

Individual evidence

  1. Astronomical Constants ( Memento from June 20, 2019 in the Internet Archive ) on
  2. NSSDC Earth Fact Sheet (21.406 seconds / 60 = 0.3567 minutes, 26.3567 minutes / 60 = 0.4393 degrees)