Celestial Sphere: What we see. it contains the stars. planets. Sun. and Moon Celestial Equator- the fanciful line that divides the planet into Northern and Southern hemispheres. The heavenly equator is a similar fanciful circle around the celestial domain. besides known as the seeable existence. The heavenly equator divides the seeable existence in two. making the Northern and Southern heavenly hemispheres. This helps us turn up heavenly organic structures. Ecliptics -an fanciful line on the sky that marks the one-year way of the Sun. It is the projection of Earth’s orbit onto the heavenly domain.
Besides define the way of the Sun. the ecliptic Markss the line along which eclipses occur. the Moon and planets and asteroids wander. the Zodiac configurations live. The ecliptic is even the starting point for the heavenly co-ordinate system used by uranologists to nail the location of every star. nebula. and galaxy. Meridian-a great circle of the Earth go throughing through the poles and any given point on the earth’s surface. The half of such a circle included between the poles. Astronomy. the great circle of the celestial domain that passes through its poles and the observer’s zenith. A point or period of highest development. greatest prosperity. or the similar. an of the way manner sin the organic structure along critical energy flows. Zenith-The point on the celestial domain that is straight above the perceiver.
The upper part of the sky. The highest point above the observer’s skyline attained by a heavenly organic structure. Nadir-the point of the heavenly spherethat is straight opposite the zenithand vertically downward from the observer Celestial Poles-Either of two diametrically opposite points at which the extensions of the earth’s axis intersect the celestial domain. Either of the two points at which a due north or southbound projection of the Earth’s axis intersects the celestial sphere. The North and south heavenly poles are correspondent to Earth’s geographic poles and are used in finding right Ascension in the equatorial co-ordinate system. Depending on which hemisphere an perceiver is in. the stars and other heavenly objects appear to go around one time around the North or south heavenly pole every 24 hours. an consequence produced by the rotary motion of the Earth on its axis.
Because of the precession of Earth’s axis. the heavenly poles bit by bit switch place in the sky over a about 26. 000-year rhythm. Solstices-As the Earth travels around the Sun in its orbit. the north-south place ( decline ) of the Sun alterations over the class of the twelvemonth due to the altering orientation of the Earth’s tilted rotary motion axes with regard to the Sun. It is this alteration in the place of the Sun that is responsible for seasons.
Solstices occur when Sun reaches maximal beginnings from the equator projected on the sky. This beginning corresponds to thetilt angle of Earth’s rotational axis with regard to its orbital plane. called the Earth’s asynclitism. either of the two times a twelvemonth when the Sun is at its greatest distance from the heavenly equator: about June 21. when the Sun reaches its northmost point on the celestial domain. or about Dec. 22. when it reaches its southernmost point. Either of the two points in the ecliptic farthest from the equator.
•Equinoxes-Either of the two points on the celestial sphere where the ecliptic ( the evident way of the Sun ) crosses the heavenly equator. The point at which the Sun’s way crosses the heavenly equator traveling from south to north is called the youthful equinox. The youthful equinox marks the nothing point in both the equatorial and ecliptic co-ordinate systems ; horizontal angular distances are measured eastward from this point.
The youthful equinox is besides known as the first point of Rams because when first devised some 2. 000 old ages ago this point occurred at the beginning of Rams in the zodiac. The point at which the Sun’s way crosses the heavenly equator traveling from north to south is called the autumnal equinox. •Longitude-Lines of longitude. called acmes. run perpendicular to lines of latitude. and all base on balls through both poles. Each longitude line is portion of a great circle. There is no obvious 0-degree point for longitude. as there is for latitude. Throughout history many different get downing points have been used to mensurate longitude. By international understanding. the meridian line through Greenwich. England. is presently given the value of 0 grades of longitude ; this acme is referred to as the Prime Meridian.
Longitude values are indicate the angular distance between the Prime Meridian and points east or west of it on the surface of the Earth. •Latitude-A line linking all the points with the same latitude value is called a line of latitude. This term is normally used to mention to the lines that represent values in whole grades. All lines of latitude are parallel to the Equator. and they are sometimes besides referred to as analogues. Analogues are every bit spaced. There are 90 grades of latitude traveling north from the Equator. and the North Pole is at 90 grades N. There are 90 grades to the South of the Equator. and the South Pole is at 90 grades S. When the directional designators are omitted. northern latitudes are given positive values and southern latitudes are given negative values.
•Right Ascension-The azimuthal angle at which the hr circleof a heavenly object is located. The rotary motion axis taken as the way of the heavenly pole. Right Ascension is normally measured in units of clip ( hours. proceedingss. and seconds ) . with one hr of clip about equal to 15° of discharge ( 360°/24 hours=15°/hour ) . •Declination-On the celestial sphere. the place of a heavenly object North or South of the heavenly equator. Declination is measured in grades along a great circle drawn through the object being measured and the North and south heavenly poles. with positive values north of the heavenly equator and negative values south of it. so that the equator itself is 0° and the North and south heavenly poles are +90° and -90° decline severally the angular distance of a heavenly organic structure north or to the South of the heavenly equator ; expressed in grades ; used with right Ascension to stipulate places on the celestial domain