The reason that objects in space don't orbit each other endlessly is primarily due to the effects of gravitational interactions and external factors. While the concept of an eternal orbit without any external influences is an idealized scenario, real-world conditions introduce factors that can disrupt or alter orbital paths over time. Here are some key reasons why objects in space don't orbit indefinitely:
Gravitational perturbations: The gravitational force between two objects in orbit is not the only force acting upon them. Other celestial bodies, such as planets, moons, or nearby stars, exert gravitational forces that can disturb the orbital paths. These perturbations cause slight changes in the orbits over time, leading to deviations from perfect, stable orbits.
Tidal forces: In close orbits, tidal forces can also play a role. Tidal forces arise due to variations in gravitational forces across the extent of an object. They can induce deformations or stress on the orbiting bodies, causing energy to dissipate over time. This energy loss leads to a gradual decay of the orbit.
Atmospheric drag: In the case of objects orbiting within a planet's atmosphere, atmospheric drag becomes a significant factor. Even at high altitudes, there are traces of atmospheric particles that can exert drag on orbiting objects, causing their orbits to decay gradually. This effect is particularly notable for satellites in low Earth orbit, which experience sufficient atmospheric drag to require periodic boosts to maintain their orbits.
Non-spherical or irregularly shaped objects: When dealing with non-spherical or irregularly shaped objects, such as asteroids or comets, the gravitational interactions can be more complex. These objects may experience uneven gravitational forces, resulting in irregular or chaotic orbits that are not indefinitely stable.
Relativity and other factors: On extremely large timescales, general relativity and other physical phenomena may come into play, leading to further modifications of orbital dynamics. However, these effects are typically negligible for most scenarios involving everyday astronomical objects.
It's important to note that while objects in space don't orbit each other endlessly, stable and long-lasting orbits can persist over vast periods, especially when significant external influences are absent or negligible.