History, unfortunately, has not preserved the names of the designers of ancient monumental structures, such as the pyramids in the Giza Valley in Egypt or the Temple of the Sun in South America. Only one thing can be said with certainty: the one who built, and especially the one who designed these structures, not only knew how to achieve ideal horizontal surfaces and clearly maintain verticals, but also perfectly mastered the orientation to the cardinal points. They definitely knew such concepts as "zenith" and "nadir". This is clearly seen in the perfect arrangement of huge structures and their impeccable proportions.
What is the zenith, nadir
In short, nadir is the opposite of zenith. But first things first. Let's orient ourselves in our earthly space. If you use a compass (in most modern smartphones equipped with a magnetic sensor, it is installed as an application, but you can also use a regular one with a magnetic needle) and face north, the picture will look like this.
The eyes of the observer will look to the north, behind - the south. Far eastern countries will lie on the right hand, and the west will lie on the left side of romantic sunsets and wild cowboys.
Straightoverhead in the very center of the celestial dome will be the zenith. Well, the nadir is its opposite, located below.
All this is simply and clearly shown in the diagram.
In what areas is the concept of nadir used
If you really want to see the exact direction to the nadir, just use the usual construction plumb line. When the load calms down and the thread freezes motionless, the tip, like an arrow, will indicate the desired direction. However, builders are more interested in the deviation of structures from verticals and horizontals, they are not interested in where the nadir is. Astronomy, on the other hand, uses this concept to denote the sides of cosmic bodies, relative to the location of a particular point on their surface.
There is another area where you can often hear the word "nadir". These are aviation and astronautics. When calculating the trajectory and directions of an aircraft or spacecraft, the nadir direction is the direction of gravity, which plays a key role in the calculations.
