Editing Tidal force (section)

{{Short description|Gravitational effect also known as the differential force and the perturbing force}}
[[File:Arp 282.png|right|300px|thumb|upright=1.5|Figure 1: Tidal interaction between the [[spiral galaxy]] [[NGC 169]] and a smaller companion<ref>
{{cite web
 | title=Hubble Views a Cosmic Interaction
 | date=February 11, 2022 | publisher=NASA | website=nasa.gov
 | url=https://www.nasa.gov/image-feature/goddard/2022/hubble-views-a-cosmic-interaction
 | access-date=2022-07-09
}}</ref>]]

The '''tidal force''' or '''tide-generating force''' is the difference in [[gravitational attraction]] between different points in a [[gravitational field]], causing bodies to be pulled unevenly and as a result are being stretched towards the attraction. It is the '''differential force''' of gravity, the net between [[gravitational force]]s, the [[derivative]] of [[gravitational potential]], the [[gradient]] of gravitational fields. Therefore tidal forces are a '''residual force''', a secondary effect of gravity, highlighting its spatial elements, making the closer near-side more attracted than the more distant far-side.

This produces a range of [[tide|tidal phenomena]], such as ocean tides. Earth's tides are mainly produced by the relative close gravitational field of the Moon 
and to a lesser extend by the stronger, but further away gravitational field of the Sun. The ocean on the side of Earth facing the Moon is being pulled by the gravity of the Moon away from [[Earth's crust]], while on the other side of Earth there the crust is being pulled away from the ocean, resulting in Earth being stretched, bulging on both sides, and having opposite [[high-tide]]s. Tidal forces viewed from Earth, that is from a [[rotating reference frame]], appear as [[centripetal force|centripetal]] and [[centrifugal force]]s, but are not caused by the rotation.<ref name="k120">{{citation | last1=Matsuda | first1=Takuya | last2=Isaka | first2=Hiromu | last3=Boffin | first3=Henri M. J. | title=Confusion around the tidal force and the centrifugal force | date=2015 | arxiv=1506.04085 | url=https://arxiv.org/abs/1506.04085 | access-date=2025-02-14 | page=}}</ref>

Further tidal phenomena include [[solid-earth tide]]s, [[tidal locking]], breaking apart of celestial bodies and formation of [[ring system]]s within the [[Roche limit]], and in extreme cases, [[spaghettification]] of objects. Tidal forces have also been shown to be fundamentally related to [[gravitational wave]]s.<ref name="arXiv 2019 p440">{{cite web | last=arXiv | first=Emerging Technology from the | title=Tidal forces carry the mathematical signature of gravitational waves | website=MIT Technology Review | date=2019-12-14 | url=https://www.technologyreview.com/2019/12/14/131574/tidal-forces-carry-the-mathematical-signature-of-gravitational-waves/ | access-date=2023-11-12}}</ref>

In [[celestial mechanics]], the expression ''tidal force'' can refer to a situation in which a body or material (for example, tidal water) is mainly under the gravitational influence of a second body (for example, the Earth), but is also perturbed by the gravitational effects of a third body (for example, the Moon). The perturbing force is sometimes in such cases called a tidal force<ref>[http://adsabs.harvard.edu/full/1977SvAL....3...96A "On the tidal force"], I. N. Avsiuk, in "Soviet Astronomy Letters", vol. 3 (1977), pp. 96–99.</ref> (for example, the [[Lunar theory#Newton|perturbing force on the Moon]]): it is the difference between the force exerted by the third body on the second and the force exerted by the third body on the first.<ref>See p. 509 in [https://archive.org/details/astronomyphysica00kutn/page/509 <!-- quote="tidal force" perturb. --> "Astronomy: a physical perspective"], M. L. Kutner (2003).</ref>