Midday point

The south point , identical to the mean midday point of the sun, or midday point for short , is a term from spherical astronomy and describes the southern intersection of the meridian with the horizon . It denotes one of the four main or cardinal points (Latin: plagae cardinales ), through which the four regions of the world (today: cardinal points ) were determined.

The south point is the zero point of counting the azimuth , the directional information measured in the horizon in the horizontal coordinate system (horizon system) . The passage of a celestial object through the meridian of the south point (i.e. an azimuth a  = 0) is the meridian passage .

In the case of the sun, because of its variable declination , this is not exactly the same as reaching its greatest height above the horizon ; This apex of the daily solar path is called the culmination , more imprecisely also the high point , highest point , climax or maximum . This is true local time noon (12 noon true local time). He can in the western parts of Germany and Switzerland, from 12 am Central European Time by almost an hour and from 12 am Central European Summer Time differ by almost two hours.

In gnomonics , the theory of sundials, the midday point is the end point of the shadow cast by the gnomon at the highest daytime sun (culmination of the sun) on the ground.

The connection between the noon points moving over the course of a year with the highest point of the sun is the noon line , the measuring line of the true noon in local time. It (like all other lines of the same true local time) forms the analemma (the 8-shaped double loop) opposite the straight line of the south point .

Demarcation

The zenith (indication of direction) denotes the point in the sky vertically above the viewer.

Middle of the sky or Latin medium coeli (English midheaven ) is the intersection of the meridian with the ecliptic (instead of the horizon).