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Earth Science A
UNIT 1: Structure of the Universe Vocabulary
| Term | Definition |
|---|---|
| apparent brightness | the observed or measured brightness of a celestial object from Earth |
| big bang theory | the theory that all energy and matter in the universe began expanding from a single point |
| blueshift | the movement of the spectral lines of an atom toward the blue region of the electromagnetic spectrum |
| cosmic microwave background radiation | the radiation that was left over after the big bang |
| Doppler effect | the change in frequency of a wave due to the motion of the source and/or receiver |
| Hertzsprung-Russel diagram | a scatter plot that shows the relationship between spectral classification, temperature, and luminosity of stars |
| luminosity | the amount of energy a star emits in a unit of time |
| nebula | a cloud in space made of gas and dust |
| nucleosynthesis | the process in which atomic nuclei are formed |
| opaque | not allowing light to pass through; not able to be seen through |
| protostar | an early stage of the birth of a star in which gas and dust have contracted to form a hot, dense core just before nucleosynthesis begins |
| quarks | the elementary particles that make up protons and neutrons |
| redshift | the movement of the spectral lines of an atom toward the red region of the electromagnetic spectrum |
| singularity | a theoretical point in space-time in which matter is compressed to a single point |
| supernova | the explosion generated in a high mass star after fusion stops, which results in the dispersion of heavy elements and the creation of a nebula |
| absorption spectrum | an electromagnetic radiation spectrum in which wavelengths of light absorbed by a substance show up as dark lines on a visible light background |
| atomic spectrum | the spectrum of wavelengths of electromagnetic radiation that are emitted or absorbed during transitions of electrons between energy levels |
| emission spectrum | an electromagnetic radiation spectrum in which wavelengths of light emitted by a substance show up as brightly colored lines |
| spectroscopy | the study of the absorption and emission of light by atoms |
| deuteron | nucleus of deuterium, with one proton and one neutron; an isotope of hydrogen |
| photon | the smallest packet of electromagnetic energy |
| chain reaction | a self-sustaining series of chemical reactions in which the products of one reaction are the reactants in the next reaction |
| critical mass | the amount of fissionable material capable of sustaining a constant rate of fission |
| nuclear fission | the process in which a heavy nucleus is split into two large fragments of comparable mass to form smaller and more stable nuclei, resulting in the release of great amounts of energy |
| nuclear fusion | the process in which lighter atomic nuclei combine to form a heavier, more stable nucleus, resulting in the release of great amounts of energy |
| transuranium element | an element that has an atomic number greater than 92, is produced in a laboratory, and is radioactive |
| solar system | system of eight planets, one dwarf planet, and other objects that revolve around the Sun. |
| free fall | the motion that occurs when gravity is the only force acting on an object |
| inertia | the natural tendency of objects to resist a change in motion |
| orbital period | the time it takes an object to complete one orbit around a central object |
| satellite | a natural or human-made object that orbits a much larger object |
| astronomical unit | the average distance from Earth to the Sun, equivalent to 1.5 x 10^11 meters |
| ellipse | an oval created by a moving point whose sum of the distances to two foci is constant |
| heliocentric model | a model of the solar system that places the Sun in the center with the planets orbiting around the Sun |
| Kepler’s first law | the law stating that the orbits of planets are ellipses with the Sun at onefocus |
| Kepler’s second law | the law stating that the speed of a planet varies, such that a planet sweeps out an equal area in equal time frames |
| Kepler’s third law | the law that relates a planet's orbital period and its average distance from the Sun |
Created by:
uservia
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