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A numerical model of the Solar System is a set of mathematical equations, which, when solved, give the approximate positions of the planets as a function of time. Attempts to create such a model established the more general field of celestial mechanics.
Predicting the position of the planets in the sky was already performed in ancient times. Careful observations and geometrical calculations produced a model of the motion of the Solar System known as the Ptolemaic system, which was based on an Earth-centered system.
SPICE (Spacecraft Planet Instrument C-matrix Events) is a NASA ancillary information system used to compute geometric information used in planning and analyzing science observations obtained from robotic spacecraft. It is also used in planning missions and conducting numerous engineering functions needed to carry out those missions.
The heliocentric ecliptic system describes the planets' orbital movement around the Sun, and centers on the barycenter of the Solar System (i.e. very close to the center of the Sun). The system is primarily used for computing the positions of planets and other Solar System bodies, as well as defining their orbital elements.
Better values of the planets' masses had been found since DE118/DE200, further refining the perturbations. Lunar Laser Ranging accuracy was improved, giving better positions of the Moon. DE403 covered the time span early 1599 to mid 2199. [22] DE404 [23] was released in 1996. A so-called Long Ephemeris, this condensed version of DE403 covered ...
Jet Propulsion Laboratory (JPL) ephemerides do not use things such as periods, eccentricities, etc. [2] Instead, JPL integrates the equations of motion in Cartesian coordinates (x,y,z), and adjusts the initial conditions in order to fit modern, highly accurate measurements of planetary positions. [2]
A NASA explanation—also attributed to Neil J. Cornish; Explanation of Lagrange points—John Baez; Locations of Lagrange points, with approximations—David Peter Stern; An online calculator to compute the precise positions of the 5 Lagrange points for any 2-body system—Tony Dunn
The concept of the position angle is inherited from nautical navigation on the oceans, where the optimum compass course is the course from a known position s to a target position t with minimum effort. Setting aside the influence of winds and ocean currents, the optimum course is the course of smallest distance between the two positions on the ...