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  2. VSOP model - Wikipedia

    en.wikipedia.org/wiki/VSOP_model

    It is customary to develop them into periodic series which are a function of time, e.g. (a+bt+ct 2 +...)×cos(p+qt+rt 2 +...) and so forth, one for each planetary interaction. The factor a in the preceding formula is the main amplitude, the factor q the main angular velocity, which is directly related to a harmonic of the driving force, that is ...

  3. Astronomical coordinate systems - Wikipedia

    en.wikipedia.org/wiki/Astronomical_coordinate...

    Angles in the hours ( h), minutes ( m), and seconds ( s) of time measure must be converted to decimal degrees or radians before calculations are performed. 1 h = 15°; 1 m = 15′; 1 s = 15″ Angles greater than 360° (2 π ) or less than 0° may need to be reduced to the range 0°−360° (0–2 π ) depending upon the particular calculating ...

  4. Lunar Laser Ranging experiments - Wikipedia

    en.wikipedia.org/wiki/Lunar_Laser_Ranging...

    The Lunar Laser Ranging data is collected in order to extract numerical values for a number of parameters. Analyzing the range data involves dynamics, terrestrial geophysics, and lunar geophysics. The modeling problem involves two aspects: an accurate computation of the lunar orbit and lunar orientation, and an accurate model for the time of ...

  5. Orbit determination - Wikipedia

    en.wikipedia.org/wiki/Orbit_determination

    The central bodies are the sources of the gravitational forces, like the Sun, Earth, Moon and other planets. The orbiting bodies, on the other hand, include planets around the Sun, artificial satellites around the Earth, and spacecraft around planets. Newton's laws of motion will explain the trajectory of an orbiting body, known as Keplerian orbit.

  6. Satellite ground track - Wikipedia

    en.wikipedia.org/wiki/Satellite_ground_track

    A satellite whose orbital period is an integer fraction of a day (e.g., 24 hours, 12 hours, 8 hours, etc.) will follow roughly the same ground track every day. This ground track is shifted east or west depending on the longitude of the ascending node, which can vary over time due to perturbations of the orbit. If the period of the satellite is ...

  7. Orbital eccentricity - Wikipedia

    en.wikipedia.org/wiki/Orbital_eccentricity

    The mean eccentricity of an object is the average eccentricity as a result of perturbations over a given time period. Neptune currently has an instant (current epoch ) eccentricity of 0.011 3 , [ 13 ] but from 1800 to 2050 has a mean eccentricity of 0.008 59 .

  8. Numerical model of the Solar System - Wikipedia

    en.wikipedia.org/wiki/Numerical_model_of_the...

    To calculate the accelerations the gravitational attraction of each body on each other body is to be taken into account. As a consequence the amount of calculation in the simulation goes up with the square of the number of bodies: Doubling the number of bodies increases the work with a factor four.

  9. Solar zenith angle - Wikipedia

    en.wikipedia.org/wiki/Solar_zenith_angle

    The solar zenith angle is the zenith angle of the sun, i.e., the angle between the sun’s rays and the vertical direction.It is the complement to the solar altitude or solar elevation, which is the altitude angle or elevation angle between the sun’s rays and a horizontal plane.