That's the observer's 'zenith'. Since it's referenced to the
"observer's head", each observer has a different zenith.
The zenith.
The microscope has two systems of lenses: the ocular lens into which the observer looks; and objective lenses placed directly above the object being observed.
The local zenith is perpendicular to the rotation axis of the Earth at a specific location. It represents the point directly above an observer, pointing towards the celestial sphere. The rotation axis of the Earth is an imaginary line around which the Earth spins.
The epicenter of an earthquake is directly above the focus or hypocenter, which is the point where the seismic waves originate within the Earth. It is typically located on the Earth's surface directly vertically above the focus.
The earth's axis of rotation is tilted relative to its orbit around the sun, causing Polaris to align with the earth's axis. When an observer measures the altitude of Polaris above the horizon, they can determine their latitude because Polaris' altitude corresponds to the observer's angular distance from the North Pole.
The zenith.
The imaginary point located directly above an observer's head is called the "zenith." In celestial navigation and astronomy, the zenith is the point in the sky that is vertically aligned with the observer's position on the Earth's surface. It represents the highest point in the sky relative to the observer's location.
The zenith.
Zenith
If an observer on Earth sees Polaris on the horizon, they are located at the equator. Polaris, also known as the North Star, is positioned nearly directly above the North Pole, so it is only visible at higher latitudes in the Northern Hemisphere. At the equator, Polaris would appear to be at the horizon, indicating the observer's latitude is 0 degrees.
The celestial equator is an imaginary circle created by extending Earth's equator into space. Zenith is an imaginary point in the sky directly above and observer on earth.
That's called the observer's "zenith".
The high point in the sky is likely the zenith, which is the point directly above an observer. It is the highest point in the sky that can be seen from a specific location. The zenith changes as you change your position on Earth.
The microscope has two systems of lenses: the ocular lens into which the observer looks; and objective lenses placed directly above the object being observed.
The hypocentre is the point inside the Earth where an earthquake starts. The point on the Earth's surface directly above this is the epicentre.
The epicenter is the point on the earth's surface directly above the earthquake's origin.
The local zenith is perpendicular to the rotation axis of the Earth at a specific location. It represents the point directly above an observer, pointing towards the celestial sphere. The rotation axis of the Earth is an imaginary line around which the Earth spins.