Search results
Results from the WOW.Com Content Network
Zenith stars (also "star on top", "overhead star", "latitude star") [8] are stars whose declination equals the latitude of the observers location, and hence at some time in the day or night pass culminate (pass) through the zenith. When at the zenith the right ascension of the star equals the local sidereal time at your location.
For example, in the Sun the convection at the base of the convection zone, near the core, is adiabatic but that near the surface is not. The mixing length theory contains two free parameters which must be set to make the model fit observations, so it is a phenomenological theory rather than a rigorous mathematical formulation.
Celestial mechanics is the branch of astronomy that deals with the motions of objects in outer space. Historically, celestial mechanics applies principles of physics (classical mechanics) to astronomical objects, such as stars and planets, to produce ephemeris data.
An observer standing on Earth's equator visualizes the celestial equator as a semicircle passing through the zenith, the point directly overhead. As the observer moves north (or south), the celestial equator tilts towards the opposite horizon. The celestial equator is defined to be infinitely distant (since it is on the celestial sphere); thus ...
The time of culmination (when the object culminates) is often used to mean upper culmination. [2] [3] [4] An object's altitude (A) in degrees at its upper culmination is equal to 90 minus the observer's latitude (L) plus the object's declination (δ): A = 90° − L + δ. This equation is the basis for the meridian altitude method for latitude ...
The north and south celestial poles appear permanently directly overhead to observers at Earth's North Pole and South Pole, respectively. As Earth spins on its axis, the two celestial poles remain fixed in the sky, and all other celestial points appear to rotate around them, completing one circuit per day (strictly, per sidereal day ).
A star chart drawn 5000 years ago by the Indians in Kashmir, which also depict a supernova for the first time in human history. [7] The Nebra sky disk , a 30 cm wide bronze disk dated to 1600 BC, bears gold symbols generally interpreted as a sun or full moon, a lunar crescent, several stars including the Pleiades cluster and possibly the Milky Way.
The angle of a celestial body with the zenith is the zenith angle (in astronomy, commonly referred to as the zenith distance).A body's angular position can also be given in terms of altitude, the angle above the geometric horizon; the altitude and the zenith angle are thus related by =.