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In the Understanding Orbits section I've described a "range of" parabolic and hyperbolic orbits.
Is that accurate?
Or -- from a given firing height, with a given mass -- is there:
Note both a parallel firing direction, and the "tilted cannon" discussed in the next Talk subject.
Wikipedia currently gives the definition of orbit as follows: "In physics, an orbit is the gravitationally curved path of an object around a point in space..."
It is unclear what "around" means in this definition, but any meaning of "around" seems incorrect. If "around" is meant to imply that an orbit is a path traversing all 360° of arc surrounding a point, that implies that hyperbolic orbits are not orbits, and that is incorrect. If "around" is meant to imply that an orbit is a path which forms a concavity containing at least one point, then that contributes nothing to the definition. And if "around" is meant to imply that an orbit has a special affinity with a specific point, the barycenter, then that is a clear case of map/territory confusion -- orbits are in no way related to barycenters; only our models of orbits are related to barycenters.
I am stumped to think of a way that "around a point in space" aptly describes an orbit. I can see that one of the sources cited for Wikipedia's definition is the Encyclopædia Britannica, which describes an orbit as a path "around an attracting centre of mass". Perhaps this is the source of the problem -- Encyclopædia Britannica got the definition wrong, and the error was replicated here on Wikipedia.
-TC 47.142.130.130 ( talk) 23:17, 10 May 2017 (UTC)
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In the edits of 8 June 2017, Twinsday changed the definition of an orbit from a "path" to a "trajectory". However, the reference for the definition is https://www.britannica.com/science/orbit-astronomy, and that page describes orbit as a "path". NASA defines orbit on its website at https://www.nasa.gov/audience/forstudents/5-8/features/orbit_feature_5-8.html, and there too it is described as a "path". Furthermore, contextual clues suggest that NASA thinks of an orbit as a path. For instance, NASA's orbital elements page at https://spaceflight.nasa.gov/realdata/elements/ uses the phrase "an orbit and a satellite's position within the orbit", which makes sense if an orbit is a path, but not if it is a trajectory. I think this is a case of Wikipedia getting ahead of the literature. I suspect that in practice, "orbit" is ambiguous, with the "trajectory" meaning primary and the "path" meaning secondary. However, the literature does not reflect current practice and unambiguously describes "orbit" as a path. Therefore, I believe Twinsday's edits were premature. Would anyone object if I reverse them? 47.142.130.130 ( talk) 16:58, 19 September 2017 (UTC)
However because of influence of other bodies (mainly gravitational, but also due to magnetic influences and radiation pressure or Solar and Stellar wind), bodies never being perfectly uniform in density and shape (see for example figure of Earth), or due to loss of mass (best example being comets or rockets), even closely repeating trajectories (commonly referred as orbits), are perturbed and show slow gradual changes in time. Such bodies are still modeled using repeating trajectory parameters, but with orbit parameters (elements) slowly varying over days and years.
So, we either have Newtonian orbits or General Relativistic orbits? Rubbish! Last I heard, Newtonian gravity works instantaneously and simply fails to adequately describe solar system dynamics. Special Relativity (or modified Newtonian Physics with a finite speed of interaction, c) is just as much Relativity as GR is. And then we have the FALSE assertion that orbits are in planes. THEY.ARE.NOT. (except for simple 2-body systems). The Relativity section needs a rewrite and the Orbital Planes section should be removed - its content is false, misleading and trivial. 71.31.150.130 ( talk) 14:58, 30 January 2018 (UTC)
I'd like to link from another article to an explanation of why many earth-observing satellites have "polar holes", areas near the poles where they cannot gather data (obviously not the ones in polar orbits). Can anyone point me to a good explanation of this, preferably in a Wikpedia article? HLHJ ( talk) 04:30, 25 February 2020 (UTC)
Orbital shell (spaceflight) → Orbit – The article Orbital shell (spaceflight) fails WP:GNG to have its own standalone article. I think that the content in that article can easily be explained in the context of Orbit, and the "Orbit" article is of a reasonable size that the merging of "Orbital shell (spaceflight)" will not cause any problems as far as article size is concerned. -- Soumyabrata stay at home wash your hands to protect from coronavirus 12:33, 7 April 2020 (UTC)
I've tagged "The paths of all the star's satellites are elliptical orbits about that barycenter" becaues I think that's a bad approximation of what really happens with respect to the Earth's orbit. Since our orbit is much closer to the Sun that Jupiter is, it would be more accurate to just say the Earth orbits the Sun, rather than the barycenter of the solar system. See the first answer to [1], which seems like the correct explanation. — Amakuru ( talk) 21:04, 13 September 2020 (UTC)
Kepler,s laws 2409:4042:D84:DEEC:0:0:618B:5213 ( talk) 14:53, 13 January 2022 (UTC)