|
3789 Zhongguo
3789 Zhongguo, provisional designation ', is a resonant asteroid from outermost region of the asteroid belt, approximately in diameter. It was discovered in 1928 by Chinese astronomer Zhang Yuzhe at the Yerkes Observatory in Williams Bay, Wisconsin, in the United States. Originally named "China", the asteroid became lost and its name was transferred to another asteroid. After its re-discovery in 1986, it was named Zhongguo, which is the Chinese word for "China". The T/ X k-type asteroid is the namesake of the resonant Zhongguo group, located in the asteroid belt's Hecuba gap. It has a short rotation period of 3.8 hours. Discovery and re-discovery While studying in Chicago, Chinese astronomer Zhang Yuzhe observed an unknown asteroid, provisionally designated ' for the first time on 25 October 1928. After it was (prematurely) given the number 1125, he named it "China" or "中国" (''Zhōngguó'') in honor of his native country. As it was not observed beyond its init ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhang Yuzhe
Zhang Yuzhe (; 16 February 1902 – 21 July 1986), also known as Yu-Che Chang, was a Chinese astronomer and director of the Purple Mountain Observatory who is widely regarded as the father of modern Chinese astronomy. He studied the light curves of asteroids, and thus their rotation periods. He also researched the variable star CZ Cassiopeiae and the evolution of the orbit of Comet Halley. Zhang discovered three comets and is credited under the name Y. C. Chang by the Minor Planet Center for the discovery of one minor planet, the outer main-belt asteroid 3789 Zhongguo. Biography Zhang was born in Fuzhou in the Minhou county, Fujian province in 1902. In 1919, he gained entrance to Tsinghua University. Graduating in 1923, he traveled to the United States where he began graduate studies at the University of Chicago in 1925, receiving his Ph.D. in 1929. Later that year, he returned to China and accepted a teaching post at the National Central University in Nanjing, China (now k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhongguo
China, officially the People's Republic of China (PRC), is a country in East Asia. With a population exceeding 1.4 billion, it is the second-most populous country after India, representing 17.4% of the world population. China spans the equivalent of five time zones and borders fourteen countries by land across an area of nearly , making it the third-largest country by land area. The country is divided into 33 province-level divisions: 22 provinces, 5 autonomous regions, 4 municipalities, and 2 semi-autonomous special administrative regions. Beijing is the country's capital, while Shanghai is its most populous city by urban area and largest financial center. Considered one of six cradles of civilization, China saw the first human inhabitants in the region arriving during the Paleolithic. By the late 2nd millennium BCE, the earliest dynastic states had emerged in the Yellow River basin. The 8th–3rd centuries BCE saw a breakdown in the authority of the Zho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic against the fixed stars, background of stars – specifically the Zodiac constellations. The planets of the Solar System can also be seen along the ecliptic, because their orbital planes are very close to Earth's. The Moon's orbital plane is also similar to Earth's; the ecliptic is so named because the ancients noted that eclipses only occur when the Moon is crossing it. The ecliptic is an important Plane of reference, reference plane and is the basis of the ecliptic coordinate system. Ancient scientists were able to calculate Earth's axial tilt by comparing the ecliptic plane to that of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Inclination
Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Earth directly above the Equator, the plane of the satellite's orbit is the same as the Earth's equatorial plane, and the satellite's orbital inclination is 0°. The general case for a circular orbit is that it is tilted, spending half an orbit over the northern hemisphere and half over the southern. If the orbit swung between 20° north latitude and 20° south latitude, then its orbital inclination would be 20°. Orbits The inclination is one of the six orbital elements describing the shape and orientation of a celestial orbit. It is the angle between the orbital plane and the plane of reference, normally stated in degrees. For a satellite orbiting a planet, the plane of reference is usually the plane containing the planet's equator. For pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Eccentricity
In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit (or capture orbit), and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the Galaxy. Definition In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit. The eccentricity of this Kepler orbit is a non-negative number that defines its shape. The eccentricity may take the following values: * Circular orbit: * Elliptic orbit: * Parabolic trajectory: * Hyperbolic trajectory: The eccentricity is given by e = \sqrt where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semi-major Axis
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longest semidiameter or one half of the major axis, and thus runs from the centre, through a focus, and to the perimeter. The semi-minor axis (minor semiaxis) of an ellipse or hyperbola is a line segment that is at right angles with the semi-major axis and has one end at the center of the conic section. For the special case of a circle, the lengths of the semi-axes are both equal to the radius of the circle. The length of the semi-major axis of an ellipse is related to the semi-minor axis's length through the eccentricity and the semi-latus rectum \ell, as follows: The semi-major axis of a hyperbola is, depending on the convention, plus or minus one half of the distance between the two branches. Thus it is the distance from the ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Background Asteroid
An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An asteroid family is a more specific term than asteroid group whose members, while sharing some broad orbital characteristics, may be otherwise unrelated to each other. General properties Large prominent families contain several hundred recognized asteroids (and many more smaller objects which may be either not-yet-analyzed, or not-yet-discovered). Small, compact families may have only about ten identified members. About 33% to 35% of asteroids in the main belt are family members. There are about 20 to 30 reliably recognized families, with several tens of less certain groupings. Most asteroid families are found in the main asteroid belt, although several family-like groups such as the Pallas family, Hungaria family, and the Phocaea fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minor Planet Circulars
The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function The Minor Planet Center is the official worldwide organization in charge of collecting observational data for minor planets (such as asteroids), calculating their orbits and publishing this information via the '' Minor Planet Circulars''. Under the auspices of the International Astronomical Union (IAU), it operates at the Smithsonian Astrophysical Observatory, which is part of the Center for Astrophysics along with the Harvard College Observatory. The MPC runs a number of free online services for observers to assist them in observing minor planets and comets. The complete catalogue of minor planet orbits (sometimes referred to as the "Minor Planet Catalogue") may also be freely downloaded. In addition to astrometric data, the MPC coll ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minor Planet Center
The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function The Minor Planet Center is the official worldwide organization in charge of collecting observational data for minor planets (such as asteroids), calculating their orbits and publishing this information via the '' Minor Planet Circulars''. Under the auspices of the International Astronomical Union (IAU), it operates at the Smithsonian Astrophysical Observatory, which is part of the Center for Astrophysics along with the Harvard College Observatory. The MPC runs a number of free online services for observers to assist them in observing minor planets and comets. The complete catalogue of minor planet orbits (sometimes referred to as the "Minor Planet Catalogue") may also be freely downloaded. In addition to astrometric data, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1125 China
1125 China ( ''prov. designation'': ) is a dark background asteroid from the outer regions of the asteroid belt. It was discovered on 30 October 1957, by astronomer Zhāng Yùzhé (Y. C. Chang, 张钰哲) at the Chinese Purple Mountain Observatory (紫金山天文台) in Nanjing, and named in honor of the country China. The assumed C-type asteroid has a short rotation period of 5.4 hours and measures approximately in diameter. Its name and number were actually taken from another asteroid that was considered a lost asteroid at the time, but was eventually rediscovered and given the new designation 3789 Zhongguo. "Zhongguo" means "China" in Chinese (). Orbit and classification ''China'' is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the outer asteroid belt at a distance of 2.4–3.8 AU once every 5 years and 6 months (2,019 days; semi-major axis of 3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purple Mountain Observatory
The Purple Mountain Observatory (), also known as Zijinshan Astronomical Observatory, is an astronomical observatory located on the Purple Mountain in the east of Nanjing. The observatory is responsible for calculating the official Chinese calendar of mainland China. Description The Purple Mountain Observatory was established in 1934 funded by the Nationalist Government of the Republic of China and administered by Academia Sinica. The longtime director of the observatory from 1950 to 1984 was Chinese astronomer Zhang Yuzhe (, 1902–1986, also known as Y. C. Chang). By the late 1980s, increasing light pollution in Nanjing meant Purple Mountain was no longer viable as a working observatory. It has since shifted its focus to public education, with much of the actual scientific work being carried out in its five branch observatories located at Qinghai (in Delingha), Ganyu, Xuyi, Honghe (in Jiamusi), and Qingdao. The Minor Planet Center credits the observatory, simply r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
