Search results
Results From The WOW.Com Content Network
The astronomical meridian is also determined by the zenith, and is defined as a circle on the celestial sphere that passes through the zenith, nadir, and the celestial poles. A zenith telescope is a type of telescope designed to point straight up at or near the zenith, and used for precision measurement of star positions, to simplify telescope ...
Nadir also refers to the downward-facing viewing geometry of an orbiting satellite, [2] such as is employed during remote sensing of the atmosphere, as well as when an astronaut faces the Earth while performing a spacewalk. A nadir image is a satellite image or aerial photo of the Earth taken vertically.
In astronomy, the meridian is the great circle passing through the celestial poles, as well as the zenith and nadir of an observer's location. Consequently, it contains also the north and south points on the horizon , and it is perpendicular to the celestial equator and horizon.
Horizontal coordinates use a celestial sphere centered on the observer. Azimuth is measured eastward from the north point (sometimes from the south point) of the horizon; altitude is the angle above the horizon.
A zenith camera is an astrogeodetic telescope used today primarily for the local surveys of Earth's gravity field. Zenith cameras are designed as transportable field instruments for the direct observation of the plumb line ( astronomical latitude and longitude ) and vertical deflections .
The solar zenith angle is the zenith angle of the sun, i.e., the angle between the sun’s rays and the vertical direction.It is the complement to the solar altitude or solar elevation, which is the altitude angle or elevation angle between the sun’s rays and a horizontal plane.
To determine the zenith point of the circle, the telescope was directed vertically downwards at a basin of mercury, the surface of which formed an absolutely horizontal mirror. The observer saw the horizontal wire and its reflected image, and moving the telescope to make these coincide, its optical axis was made perpendicular to the plane of ...
The zenith hatch was originally intended to be the permanent docking connector for the now canceled Centrifuge Accommodations Module (CAM). When the Space Shuttle flew the Multi-Purpose Logistics Modules (MPLMs) to the station, the MPLM would be temporarily berthed to the nadir mechanism of Harmony . [ 28 ]