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A particular form of open curve belonging to the family of curves known as conic sections. It is encountered in astronomy in two main contexts. First, it is one of the shapes that can be taken by the orbit of a body moving under the influence of a central gravitational force, such as a comet when it approaches the Sun. Second, the surface obtained by rotating a parabola, a paraboloid, is commonly used as the shape for the primary mirror in a reflecting telescope. Images formed by such parabolic mirrors, in contrast to spherical mirrors, do not suffer from spherical aberration.
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