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The official planetary K p-index is derived by calculating a weighted average of K-indices from a network of 13 geomagnetic observatories at mid-latitude locations.Since these observatories do not report their data in real-time, various operations centers around the globe estimate the index based on data available from their local network of observatories.
The Planetary Data System (PDS) is a distributed data system that NASA uses to archive data collected by Solar System missions. The PDS is an active archive that makes available well documented, peer reviewed planetary data to the research community. [1] The data comes from orbital, landed and robotic missions and ground-based support data ...
In astronomy and celestial navigation, an ephemeris (/ ɪ ˈ f ɛ m ə r ə s /; pl. ephemerides / ˌ ɛ f ə ˈ m ɛ r ə d iː z /; from Latin ephemeris 'diary' and Greek ἐφημερίς (ephemeris) 'diary, journal') [1] [2] [3] is a book with tables that gives the trajectory of naturally occurring astronomical objects as well as artificial satellites in the sky, i.e., the position (and ...
The Earth Similarity Index (ESI) is a proposed characterization of how similar a planetary-mass object or natural satellite is to Earth. It was designed to be a scale from zero to one, with Earth having a value of one; this is meant to simplify planet comparisons from large databases. The scale has no quantitative meaning for habitability.
The choice of solar mass, M ☉, as the basic unit for planetary mass comes directly from the calculations used to determine planetary mass.In the most precise case, that of the Earth itself, the mass is known in terms of solar masses to twelve significant figures: the same mass, in terms of kilograms or other Earth-based units, is only known to five significant figures, which is less than a ...
The astronomical unit of time is a time interval of one day (D) of 86400 seconds.The astronomical unit of mass is the mass of the Sun (S).The astronomical unit of length is that length (A) for which the Gaussian gravitational constant (k) takes the value 0.017 202 098 95 when the units of measurement are the astronomical units of length, mass and time.
Jet Propulsion Laboratory Development Ephemeris (abbreviated JPL DE (number), or simply DE (number)) designates one of a series of mathematical models of the Solar System produced at the Jet Propulsion Laboratory in Pasadena, California, for use in spacecraft navigation and astronomy. The models consist of numeric representations of positions ...
The semi-analytic planetary theory VSOP (French: Variations Séculaires des Orbites Planétaires) is a mathematical model describing long-term changes (secular variation) in the orbits of the planets Mercury to Neptune. The earliest modern scientific model considered only the gravitational attraction between the Sun and each planet, with the ...