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In astrodynamics, an orbit equation defines the path of orbiting body around central body relative to , without specifying position as a function of time.Under standard assumptions, a body moving under the influence of a force, directed to a central body, with a magnitude inversely proportional to the square of the distance (such as gravity), has an orbit that is a conic section (i.e. circular ...
The Hill sphere (gravitational sphere of influence) of the Earth is about 1,500,000 kilometers (0.01 AU) in radius, or approximately four times the average distance to the Moon. [12] [nb 2] This is the maximal distance at which the Earth's gravitational influence is stronger than the more distant Sun and planets. Objects orbiting the Earth must ...
Thus the orbital period in low orbit depends only on the density of the central body, regardless of its size. So, for the Earth as the central body (or any other spherically symmetric body with the same mean density, about 5,515 kg/m 3, [2] e.g. Mercury with 5,427 kg/m 3 and Venus with 5,243 kg/m 3) we get: T = 1.41 hours
Orbital mechanics is a core discipline within space-mission design and control. Celestial mechanics treats more broadly the orbital dynamics of systems under the influence of gravity, including both spacecraft and natural astronomical bodies such as star systems, planets, moons, and comets.
For Earth, orbital eccentricity e ≈ 0.016 71, apoapsis is aphelion and periapsis is perihelion, relative to the Sun. For Earth's annual orbit path, the ratio of longest radius (r a) / shortest radius (r p) is = +
For a circular orbit around a central body, where the centripetal force provided by gravity is F = mv 2 r −1: = = =, where r is the orbit radius, v is the orbital speed, ω is the angular speed, and T is the orbital period.
The orbital period is equal to that for a circular orbit with the orbital radius equal to the semi-major axis For a given semi-major axis the orbital period does not depend on the eccentricity (See also: Kepler's third law ).
The longitude of the ascending node, also known as the right ascension of the ascending node, is one of the orbital elements used to specify the orbit of an object in space. Denoted with the symbol Ω , it is the angle from a specified reference direction, called the origin of longitude , to the direction of the ascending node (☊), as ...