Chinese term】 solar parallax Foreign entry】 【solar parallax for those】 【Wu Shouxian Astronomical constants to indicate the exact name should be the solar equator horizon parallax. It can be defined as: , Where is the radius of the Earth's equator, a center of mass is the Earth-Moon system, the average distance of the sun, the astronomical unit. Before the advent of radar astronomy, the Earth-Moon system is the center of mass of the sun by measuring the distance to calculate the solar parallax. The astronomical unit is a measure of the distance between objects within the solar system the basic unit, but also the determination of the baseline stellar trigonometric parallax for centuries, has been the determination of solar parallax astrometry of important issues. Method of determination of solar parallax solar system planets are mainly observed. When the planets (or asteroids) closest to the Earth when the planet first Sunday of the equatorial horizon measured parallax to determine distance from the planet Earth, and then under the theory of celestial mechanics obtained by the planet on the Earth and the Sun-Earth distance The ratio of the average distance, inquire of the sun, as the difference. For this reason, astronomers have been washed in the transit of Venus ﹑ ﹑ asteroid Mars red, etc. (see the apparent motion of planets) Sky favorable time of the observation time with the planned, in particular the work of the famous 1931 Eros 1930 Sing Chong global joint observation, 23 Observatory worldwide (including China's Sheshan Station of Shanghai Astronomical Observatory) to participate in observation. According to this observation, Jones had i (^ 0 = 8790. The most accurate observations of modern astronomical methods using radar, the first determination of an astronomical unit away from the light line a, in the case of the speed of light c is known, obtained a, re derived from a. In Newcomb's astronomical constants obtained in 880 solar parallax, the value in use from 1896 to 1967. In 1964, the International Astronomical Union system of astronomical constants, the solar parallax as derived constant, = arcsin (ae / a) = 879405, this value since 1968, has been to use 1983. In 1976, the International Astronomical Union system of astronomical constants, the solar parallax is still a derived constant, taken as 8,794,148, it unified since 1984 used. The last two parameters are determined based on a planet beyond radar range, by a value derived from.
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Measure solar time difference
From Kepler's third law of planetary distances can be calculated relative values, in fact, this law describes the solar system, according to "scale model." If the Sun to the Earth's average distance (called the astronomical unit) is expressed in units of a planet's average distance to the sun, then Kepler's third law can be written as: a ^ 3 = T ^ 2 Where a is the average distance of the planet to the sun, T is the planet's rotational period in years. This means that, as long as that period of revolution of the planets, it can be calculated several astronomical units from the sun. This shows that the astronomical unit is a measure of the size of the ruler the solar system. Therefore, the distance determination of the Earth to the sun is extremely important. The distance from Earth to the sun, the sun is often used to represent the geocentric parallax. The so-called geocentric parallax refers to the inclination of Earth's radius of celestial bodies. Aware of this angle, they know the length of the radius of the Earth, the Earth's distance to the object it is easy to obtain, because this is only solution right triangle problems. But the difficulty is that the sun is far away from the earth, directly determine its geocentric parallax, the error large. So astronomers to find planets instead parallax, because, according to Kepler's third law, can be calculated from the planet's parallax solar parallax return. After Cassini, the 1704 horse-drawn observations of Mars obtained by the end of the sun's parallax 10 "or so, in 1719 Brad was mine for the solar parallax obtained by 10" around 1715 in Rakai was 10 "2 The data . These results are not as Cassini measured 9 "5 accurate. Harley has long made use of the transit of Venus to the measured solar parallax approach. To observe the 1761 and 1769 the transit of Venus, astronomers have made full preparations in advance, they organized many expeditions around the world in the hope of observing under the best conditions. Unfortunately, the complex factors affecting the accuracy of observation. When the transit of Venus in 1761, the team observed the value of solar parallax obtained very different, small 7 "5, large 10" 5. But astronomers are struggling more than tension, the observation of a significant improvement in 1769. After this observation more than 200 papers published, most results are in 8 "5 8" to 8, the French astronomer Pange Lei (AD 1711 ~ 1796) comprehensive analysis of all the data published in 1775, the last result, solar parallax of 8 "8. This result has not been immediately recognized, as we finally recognized by the international astronomical community until 1967, the data are used.
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Encyclopedia of Astronomy
taiyang shicha Solar parallax solar parallax Astronomical constants to □ □ said the exact name should be the solar equator horizon parallax. It can be defined as: □, where □ □ equatorial radius of the Earth, A Department of the Earth-Moon center of mass is the average distance of the sun, the astronomical unit. Before the advent of radar astronomy, the Earth-Moon system center of mass of the sun by measuring the solar parallax distance to the projected □ □. The astronomical unit is a measure of the distance between objects within the solar system the basic unit, but also the determination of the baseline stellar trigonometric parallax for centuries, has been the determination of solar parallax astrometry of important issues. □ □ determination of solar parallax method is mainly observed solar system planets. When the planets (or asteroids) closest to the Earth when the planet first Sunday of the equatorial horizon measured parallax to determine distance from the planet Earth, and then under the theory of celestial mechanics obtained by the planet on the Earth and the Sun-Earth distance The ratio of the average distance, inquire of the sun, as the difference. For this reason, astronomers in the transit of Venus, Mars red, red and other asteroids (see apparent motion of planets) Sky favorable moment in the time of planned observations, in particular the work of the famous 1930 Eros 1931 Chong global joint observation, 23 Observatory worldwide (including China's Sheshan Station of Shanghai Astronomical Observatory) to participate in observation. According to this observation, Jones had □ = 8 □ 790. The most accurate observations of modern astronomical methods using radar, the first determination of an astronomical unit away from the light line □ A, in the case of the speed of light c is known, obtained A, then from A to export □ □. Newcomb's astronomical constants in the solar parallax to take 8 □ 80, this value in use from 1896 to 1967. International Astronomical Union in 1964, the system of astronomical constants, the solar parallax as derived constant, □ □ = arcsin (ae / A) = 8 □ 79405, this value since 1968, has been use to 1983. International Astronomical Union in 1976, the system of astronomical constants, the solar parallax is still a derived constant, taken as 8 □ 794148, it will uniformly applied since 1984. The latter two parameters are determined according to planetary radar ranging □ A later, through the A values derived from. (Wu Shouxian)