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Nuclear fusion

The process by which two or more small nuclei fuse to make a bigger nucleus

Nuclear fission

The process by which a large nucleus is split into smaller nuclei

Critical mass

The amount of isotope necessary to sustain a chain reaction

Absolute magnitude

The brightness of a star, corrected for distance, aon a scale of -8 to +19. The smaller the number, the brighter the star.

Apparent magnitude

The brightness of a star as seen in the night sky. The smaller the number, the brighter the star.

Light year

The distance light could travel along a straight line in one year


A large ensemble of stars, all interacting through the gravitational force and orbiting around a common center

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