The zenith.
No, the celestial equator does not always pass directly overhead. The position of the celestial equator in the sky is determined by the observer's latitude on Earth. If the observer is located at the equator, the celestial equator will pass directly overhead. However, for observers at different latitudes, the celestial equator will appear at an angle to the horizon.
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.
That's the observer's 'zenith'. Since it's referenced to the "observer's head", each observer has a different zenith.
The altitude of the North Celestial Pole above the northern horizon is equal to the observer's latitude. This means that the higher the observer's latitude, the higher the North Celestial Pole will appear in the sky. For example, an observer at a latitude of 45 degrees will see the North Celestial Pole 45 degrees above the northern horizon.
Greenwich Celestial refers to the Prime Meridian as it crosses the celestial sphere above Greenwich, UK. It serves as the global reference point to measure longitude and is used in celestial navigation and astronomy.
That's called the observer's "zenith".
The point just overhead is called the zenith. The objects visible at that point depend on the date, the time of day or night, and the observer's location.
The zenith.
west
No, the celestial equator does not always pass directly overhead. The position of the celestial equator in the sky is determined by the observer's latitude on Earth. If the observer is located at the equator, the celestial equator will pass directly overhead. However, for observers at different latitudes, the celestial equator will appear at an angle to the horizon.
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.
That's the observer's 'zenith'. Since it's referenced to the "observer's head", each observer has a different zenith.
The altitude of the North Celestial Pole above the northern horizon is equal to the observer's latitude. This means that the higher the observer's latitude, the higher the North Celestial Pole will appear in the sky. For example, an observer at a latitude of 45 degrees will see the North Celestial Pole 45 degrees above the northern horizon.
Greenwich Celestial refers to the Prime Meridian as it crosses the celestial sphere above Greenwich, UK. It serves as the global reference point to measure longitude and is used in celestial navigation and astronomy.
Zenith
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.
Celestial coordinates. -- The star's latitude on the celestial sphere is the same as the Earth latitude that it seems to follow on its way aroujnd the sky. On the celestial sphere, the latitude is called "declination", and is expressed in degrees. -- The star's longitude on the celestial sphere is its angle, measured westward, from the point in the sky called the Vernal Equinox ... the point where the sun appears to cross the celestial equator in March. On the celestial sphere, the star's longitude is called "Right Ascension", and it's expressed in hours. That certainly seems confusing, but an "hour of Right Ascension" just means 15 degrees of celestial longitude. So, as the sky turns, the point directly over your head moves through the stars by 1 hour of Right Ascension every hour.