The ecliptic coordinate system isCelestial coordinate systemone of.The ecliptic coordinate system is based on the ecliptic [equivalent toRectangular coordinate system Horizontal axis of) to pass throughVernal equinoxOfCircle of yellow meridian(semicircle) is the starting circle (equivalent toLongitudinal axis）, the celestial coordinate system with the vernal equinox as the origin, itslongitudecallYellow meridian〔λ〕 Is the angular distance between the end circle and the beginning circle of the yellow meridian where the celestial body is located, that is, an arc of the ecliptic between the end circle and the beginning circle, measured counterclockwise (left-handed) on the ecliptic starting from the equinox, from 0 ° to 360 °. Its latitude is called latitude of the yellow (β), which is the direction and angular distance of the celestial body relative to the ecliptic.Starting from the ecliptic, it is 0 ° to 90 ° northward along the ecliptic (base circle).0 ° to - 90 ° to the south.The ecliptic coordinate system is mainly used for the sun, moon and planetscelestial spherePosition and movement on the.
earthAroundsunlightfunctiontrackInfinite expansion of facecelestial sphereThe big circle of the celestial sphere formed by intersection is calledEclipticThe ecliptic is also the annual view of the sunmotionRoute.Through the center of the earth and withEcliptic surfaceverticalOfstraight linecallYellow axisThe two points where the yellow axis intersects the celestial sphere are called the yellow poles, which are divided intoNorth Yellow Pole〔E〕 And the southern pole of the ecliptic [E '] are the two poles of the ecliptic.Passing through the north and south pole of the Yellow River and perpendicular to the eclipticcelestial sphereBig round cryCircle of yellow meridianA small circle on the celestial sphere parallel to the eclipticYellow latitudeCircle.Ecliptic andCelestial equatorThe two points that intersect are calledEquinoxOf which the ecliptic is relative to the celestial equatorAscending intersectioncallVernal equinox〔γ〕，Descending pointcallAutumnal equinox。The two points on the ecliptic that are 90 ° away from the equinox are calledSolstice, of which the one located north of the celestial equator is calledSolstice point, located south of the celestial equatorWinter SolsticePoint.
The ecliptic coordinates are often used in the study of precession and nutation, and their points and planes are the northern pole and the ecliptic respectively.[1]
Basic circle and basic point
The basic circle of the ecliptic coordinate system isEclipticThe basic points are the Yellow North Pole and the Yellow South Pole.
Yellow poleIs to make a straight line perpendicular to the ecliptic plane andcelestial sphereThe two intersecting points are called the Yellow North Pole and the Yellow South Pole respectively.The connection between the Yellow North Pole and the Yellow South Pole isYellow axis。
parallelYou can make countless small circles on the celestial sphere in the ecliptic, that isYellow weft circle。Numerous large circles perpendicular to the ecliptic can be made through the pole, namelyCircle of yellow meridian, of whichVernal equinoxThe yellow meridian circle of is in the ecliptic coordinate systemlongitude（Yellow meridian）Start circle of measurement
Yellow meridian
Yellow meridianThat is, in the ecliptic coordinate systemlongitude, it is a kind ofDihedral angle。It isVernal equinoxWhereCircle of yellow meridianThe angle between the plane and the plane of the yellow circle where the celestial body is located.The measurement of the yellow meridian is based on the yellow meridian circle where the vernal equinox is located as the starting circle, which is counterclockwise along the ecliptic.In terms of angle, the range is from 0 ° to 360 °.
Yellow latitude
The latitude in the ecliptic coordinate system isLine plane angle。It is the celestial body andcelestial sphereThe angle between the line of the center and the plane of the ecliptic.Latitude in YellowEcliptic surfaceIs the starting point, measured in the south and north directions, from the ecliptic plane to the Yellow North Pole is 0 °~+90 °, and from the ecliptic plane to the Yellow South Pole is 0 °~(- 90 °).
As early as Jin·Sima BiaoThe difference between the equator and the ecliptic in determining the position of celestial bodies was analyzed in the book "Records of the Later Han Dynasty · Legal Calendar · Jia Kui's Discussion Calendar"Fu AnAs soon as the sun and the moon are measured by the ecliptic, the historiographer is not the same as the sun and the moon when he is measured by the equator. Today, he is more than one day away from the sun and the moon when he is measured by the ecliptic. He is always playing for change, but he is still retreating when he thinks of the sun and the moon.In the ecliptic, you can walk freely without changingThe Five Chronicles said that 'the sun and the moon follow the Zodiac, reaching Morning Glory in the south, and Dongjing in the north. They travel once a day, and seven of thirteen degrees and nineteen minutes a month'.Today's historiographer takes the equator as the degree, not the same as the sun and the moon. His fights, morning glory, (Dongjing), and Yu ghosts get 15 degrees at the equator, and 13 and a half degrees at the eclipticThe art of the sun and the moon follows the zodiac every day, and the moon follows the nine paths.With the equator, the winter solstice is 115 degrees away from the pole.The equator is in Dou 21, and the ecliptic is in Dou 19.The two instruments are in harmony. The sun and the moon are on a journey with poor straightness.Therefore, the monthly line of well and cattle is more than 14 degrees, and it is more than 12 degrees in the corner and Lou.None of them can respond quickly. "That is to say, as far as the moon is concerned, the date and running speed of the "chord view" measured by the ecliptic and the equator are different.The same is true of other celestial bodies.
Western scholars discuss differences
Hour angleCoordinate systemThere is no direct relationship with the ecliptic coordinate system, "as de Saussure (1740-1799) said: Greek astronomy is' the ecliptic, angle, truth, anniversary '";Chinese astronomy is equator, time, average, Sunday '.According to someArched polar starThe Chinese people have never lost the constellations that change from time to time, so they can determine the positions of the sun and the moon when they are not visible. "[7] Gongji star refers toConstant display ringAnd stars in the hidden circle.The stars in the constant display circle are alwaysHorizon circleTherefore, theirShangzhongtianAnd the lower sky.Constant hidden circleThe stars inside are always below the horizon and never rise, so they cannot be seen.See the Constant Display Circle Chart: that is,Equatorial coordinate systemIt is based on the inner loop of constant display coilPolarisTo determine the time.An important feature of this system different from western astronomy is: "It isCelestial pole, equatorial, not planetary, ecliptic. "The ecliptic coordinate system isSunriseThe ecliptic eclipse is to observe the appearance and disappearance of stars near the ecliptic before sunrise or after sunset.We all remember ancient timesEgyptWell known rightSiriusThe observation of the heliocentric days.Such observation does not require knowledge of the celestial pole, meridian or equator, nor any time measuring system. It naturally leads people to be familiar with the constellations of the ecliptic, as well as the stars that are far from or near the ecliptic and appear at the same time as the ecliptic constellations. "
The equator and the ecliptic are like cars running on two tracks. They don't go the same way.The constellations of the equator and the zodiac are different from each other, just as the stops and exits of highways and ordinary highways are different.We cannot go to the expressway to find the stops and exits of ordinary roads, nor can we go to ordinary roads to find the stops and exits of expressway.Similarly, you can't goTime angle coordinate systemOftwelve nocturnal time divisionsTo find the objective basis of the twelve signs in the zodiac, you cannot find the objective basis of the twelve stars in the twelve signs of the ecliptic coordinate system.
application
Announce
edit
The ecliptic coordinate system is suitable for representing the position and movement of celestial bodies in the solar system.Since the sun itself runs on the ecliptic, its position is represented by the sun's yellow longitudeSolar yellow meridianTo represent the sun'sVisual movementIt is particularly appropriate.For example, inVernal equinoxThe sun yellow longitude is 0 °,Summer SolsticeIs 90 °,Autumnal equinox180 °,Winter SolsticeFor the movement of other celestial bodies in the 270 ° solar system, it can also be usedEcliptic coordinatesValue.For example, the planetary motion can be expressed in the ecliptic coordinate system.When the sun and the outer planetsYellow meridianWhen they are the same, they are the same;When the sun and the outer planet have a difference of 180 ° in longitude, it is an impact;When the difference is 90 °, it is square.Another example is:,MoonThe law of operation can also be expressed in the ecliptic coordinate system.When the yellow meridians of the day and the month are the same, it is the new moon, and the new moon is the first day of every lunar month;When there is a 180 ° difference between the yellow longitude of the day and the month, it is called "hope". The "hope" time is the 15th or 16th day of the lunar calendar;When there is a 90 ° difference between the yellow meridians of the day and the moon, it is the first chord;When the difference between the yellow longitude of the day and the yellow longitude of the month is 270 °, it isBottom chord。[2]
The position of celestial bodies on the celestial sphere is often measured with a set of coordinates, such as (A, Z), while in practical work, it is sometimes necessary to use another set of coordinates, which requires transformation between different coordinate systems.[3]
However, as a special star, the sun's longitude is changing year by year, which also causes the sun'sEquatorial coordinateChange of value.Vernal equinoxSolar yellow meridian0 °,Right ascensionWhen it is 0 ° or 0,Declination0 °;Summer SolsticeThe sun's yellow longitude is 90 °, the right ascension is 90 °, and the right latitude is+23 ° 26 ';Autumnal equinoxThe sun's yellow longitude is 180 °, the right ascension is 180 °, and the right latitude is 0 °;Winter SolsticeThe sun's yellow longitude is 270 °, the right ascension is 270 °, and the declination is - 23 ° 26 '.
EachCelestial coordinate systemAll have their unique properties, so they have their specific uses. In order to facilitate comparison and memory, various celestial coordinate systems are summarized in Table 2-3.
Table Comparison of four celestial coordinate systems
