Space Station >> Space Station Glossary
Space Station Glossary P
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Period-Luminosity Law:
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A relationship, which describes how the luminosity or total brightness of a Cepheid variable star depends on the period of time over which that intensity varies.
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Photometer:
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An instrument that measures the brightness of light. Astronomers use photometers to gauge the brightness of celestial objects.
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Planet:
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An object, which orbits a star. Although lesser than stars, planets are comparatively large and shine only by reflect light. Planets are complete up mostly of rock or gas, with a small, solid core.
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Pluto:
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The outmost planet in our solar system. Pluto is, on standard, about 40 times the Earth’s distance from the Sun. Pluto orbit the Sun in 248 Earth years.
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Proton:
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An absolutely charged elementary particle that resides in the nucleus of every atom.
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