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  2. Kepler orbit - Wikipedia

    en.wikipedia.org/wiki/Kepler_orbit

    An elliptic Kepler orbit with an eccentricity of 0.7, a parabolic Kepler orbit and a hyperbolic Kepler orbit with an eccentricity of 1.3. The distance to the focal point is a function of the polar angle relative to the horizontal line as given by the equation ( 13 )

  3. Orbital eccentricity - Wikipedia

    en.wikipedia.org/wiki/Orbital_eccentricity

    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.

  4. Ancient Greek astronomy - Wikipedia

    en.wikipedia.org/wiki/Ancient_Greek_astronomy

    Anaximander. The main features of Archaic Greek cosmology are shared with those found in ancient near eastern cosmology.They include (a flat) earth, a heaven (firmament) where the sun, moon, and stars are located, an outer ocean surrounding the inhabited human realm, and the netherworld (), the first three of which corresponded to the gods Ouranos, Gaia, and Oceanus (or Pontos).

  5. De motu corporum in gyrum - Wikipedia

    en.wikipedia.org/wiki/De_motu_corporum_in_gyrum

    (Translation: 'The major planets orbit, therefore, in ellipses having a focus at the center of the Sun, and with their radii (vectores) drawn to the Sun describe areas proportional to the times, altogether (Latin: 'omnino') as Kepler supposed.') (This conclusion is reached after taking as initial fact the observed proportionality between square ...

  6. Deferent and epicycle - Wikipedia

    en.wikipedia.org/wiki/Deferent_and_epicycle

    In the Hipparchian, Ptolemaic, and Copernican systems of astronomy, the epicycle (from Ancient Greek ἐπίκυκλος (epíkuklos) 'upon the circle', meaning "circle moving on another circle") [1] was a geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets.

  7. Glossary of astronomy - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_astronomy

    The fraction of an elliptical orbit 's period that has elapsed since the orbiting body passed periapsis, expressed as the angular distance from the pericenter which a fictitious body would have if it moved in a perfectly circular orbit in the same orbital period as the actual body in its elliptical orbit. Unlike the true anomaly, the mean ...

  8. Ephemeris - Wikipedia

    en.wikipedia.org/wiki/Ephemeris

    In astronomy and celestial navigation, an ephemeris (/ ɪ ˈ f ɛ m ər ɪ s /; pl. ephemerides / ˌ ɛ f ə ˈ m ɛr ɪ ˌ d iː z /; from Latin ephemeris 'diary', from Ancient Greek ἐφημερίς (ephēmerís) 'diary, journal') [1] [2] [3] is a book with tables that gives the trajectory of naturally occurring astronomical objects and artificial satellites in the sky, i.e., the position ...

  9. Orbit - Wikipedia

    en.wikipedia.org/wiki/Orbit

    An animation showing a low eccentricity orbit (near-circle, in red), and a high eccentricity orbit (ellipse, in purple). In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object [1] such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such ...