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The fact that a star can only be studied through its light may seem, at first, to impose severe limitations on the knowledge to be acquired concerning the nature of these bright pinpoints on the night sky. When Mother Goose said "Twinkle, twinkle little star, How l wonder what you are"she expressed not only the astronomer's interest in his subject, but also his continuaI battle with the atmosphere that introduces such uncertainty into his observations.

An attempt is made to interpret the ground state gamma radiation transitions due to thermal neutron capture in terms of the shell model of the nucleus. A new selection rule for magnetic multipole radiation is derived, which depends for its validity on the assumption that the orbital angular momentum of the individual particles is a good quantum number. It is found that the ground-state transitions are in general agreement with the shell models provided that the interaction between unpaired nucleons is taken into consideration.

The Euclidean distance between two points P,Q of the Euclidean n-dimensional space En is a real valued function f(P,Q) of P and Q with the following properties. Definition. A real valued function f(P,Q) of the ordered couple of points P,Q of the En that has t he properties (1), (2) is called norm distance. Usually the norm distance satisfies (3) as well (symmetric norm distance).

A non-relativistic correction to the radiative transition rate in nuclei due to the presence of extranuclear K- shell electrons is calculated. It is found that this effect is negligible in all types of multipole transitions, for small atomic numbers. The highest correction is in fact less than 0.1%; this occurs in the electric dipole transition rate at threshold energy and low atomic number. In magnetic multipole transitions, the correction increases with atomic number.