|a theory that deduces a cataclysmic birth of the universe from the observed expansion of the universe, cosmic background radiation, abundance of the elements, and the laws of physics|
|the obscuring of the light of the moon by the intervention of the earth between it and the sun, a lunar eclipse, or the obscuring of the light of the sun by the intervention of the moon between it and a point on the earth, a solar eclipse|
|1.||the act of perturbing or the state of being perturbed|
|2.||a cause of disturbance or upset|
|3.||physics a secondary influence on a system that modifies simple behaviour, such as the effect of the other electrons on one electron in an atom|
|4.||astronomy a small continuous deviation in the inclination and eccentricity of the orbit of a planet or comet, due to the attraction of neighbouring planets|
|perturbation (pûr'tər-bā'shən) Pronunciation Key
in astronomy, deviation in the motion of a celestial object caused either by the gravitational force of a passing object or by a collision with it. For example, predicting the Earth's orbit around the Sun would be rather straightforward were it not for the slight perturbations in its orbital motion caused by the gravitational influence of the other planets. The search for an eighth planet, which culminated in the discovery of Neptune, was undertaken in part because some astronomers believed that the orbit of Uranus was being gravitationally perturbed by some object beyond it.
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