Orion Glossary
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red giantA large, cool star that is going through subsidiary stages of nuclear reactions, having exhausted its hydrogen fuel supply. | |
red giant branchA region on the Hertzsprung-Russell diagram in which red giants (luminous but cool stars in the later stages of their evolution) are found. | |
rocky materialsMaterials, such as minerals and metals, that are present in Solar System bodies that require high temperatures in order to melt (cf. icy materials). | |
S |
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satelliteAn object in orbit around a larger one, e.g. a ‘moon’, or an artificial space probe orbiting a planet. | |
silicon burningThe process of silicon burning produces elements such as sulfur, argon and calcium via the fusion of silicon nuclei at the end of the life of a massive star. | |
size of the observable UniverseThat part of the wider Universe that has been able to send us light signals since the beginning of the Universe. The Universe as a whole is larger, perhaps infinitely larger, than the observable part of it. | |
solar nebulaThe hypothetical cloud of gas and dust within which the Sun and other constituents of the Solar System formed. | |
Solar SystemThe system comprising the Sun and all the bodies (planets and their satellites, dwarf planets, comets and asteroids) that orbit around it. | |
spectrumA display (such as a graph or a photograph) of the distribution of light or other types of radiation versus the wavelength (or frequency or energy) of the radiation. It indicates the intensity of light at each different wavelength. A spectrum may be a continuous spectrum or may show emission lines (emission spectrum) or absorption lines (absorption spectrum). | |