Self-gravitation

Self-gravity must be taken into account by astronomers because the bodies being dealt with are large enough to have gravitational effects on each other and within themselves. Self-gravity affects bodies passing each other in space, within the sphere defined by their Roche limit. In this way, relatively small bodies can be torn apart, though typically the effects of self-gravitation keep the smaller body intact because the smaller body becomes elongated. This has been observed on Saturn because the rings are a function of inter-particle self-gravity. Self-gravitational forces are also significant in the formation of planetesimals and indirectly the formation of planets, which is critical to understanding how planets and planetary systems form and develop over time. Self-gravity applies to a range of scales, from the formation of rings around individual planets to the formation of planetary systems. == Seismology ==

Self-gravity has implications in the field of seismology because the Earth is large enough that it can have elastic waves that can change the gravity within the Earth as the waves interact with large-scale subsurface structures. Some models depend on the use of the spectral element method, which take into account the effects of self-gravitation because it can have a large influence on results for certain receiver-source configurations and creates complications in the wave equation, particularly for long period waves. This kind of accuracy is critical in developing accurate 3D crustal models in a spherical body (Earth) in the field of seismology, which allows for more accurate and higher-quality interpretations to be drawn from data. The influence of self-gravity, and gravity, alters the importance of Primary (P) and Secondary (S) waves in seismology because when gravity is taken into account, the effects of the S wave become less significant than they would without. == Oceanography ==

Self-gravity is influential in understanding the sea level and ice caps for oceanographers and geologists, which is particularly important for anticipating the effects of climate change. The deformation of the Earth from the forces on the oceans can be calculated if the Earth is treated as fluid and the effects of self-gravity are taken into account. This is also used for the influence of ocean tide loading to be taken into account when observing the Earth's deformation response to harmonic surface loading. There has also been research done to better understand Laplace's Tidal Equations to try to understand how the deformation of the Earth and self-gravity within the ocean affect the M2 tidal constituent (the tides dictated by the Moon). == See also ==