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Space & Earth S2T4
Science: Semester 2, Term 4 Test Revision
Term | Definition |
---|---|
absolute magnitude | actual brightness of a star |
apparent magnitude | brightness of a star as seen from Earth |
black hole | the remains of a star, which forms when the force of gravity of a large neutron star is so great that not even light can escape |
galaxies | very large groups of stars and dust held together by gravity |
nebulae | clouds of dust and gas that may be pulled together by gravity and heat up to form a star |
nuclear fusion | joining together of the nuclei of lighter elements to form another element, with the release of energy |
parallax | apparent movement of close stars against the background of distant stars when viewed from different positions around the Earth’s orbit |
planetary nebula | ring of expanding gas caused by the outer layers of a star less than eight times the mass of our sun being thrown off into space |
protostar | the final stage of development of a star in which the temperature is not quite high enough for nuclear fusion to occur |
supernova | huge explosion that happens at the end of the life cycle of supergiant star. A neutron star or black hole remains. |
big bang theory | a theory which states that the universe began about 15 billion years ago with the explosive expansion of a singularity |
cosmology | the study of the beginning and end of the universe singularity a single point of immense energy present at the time of the big bang |
steady state theory | a theory which states that there was no beginning to the universe and that the universe does not change in appearance |
blue shift | shift of lines of a spectral pattern towards the blue end when a light source is moving rapidly towards the observer |
Doppler effect | observed change in frequency of a wave when the wave source and observer are moving in relation to each other |
frequency | the number of waves passing a single location in one second |
red shift | shift of lines of a spectral pattern towards the red end when the source is moving away from the observer spectrum: light from a source separated out into the sequence of colours, showing the different frequencies |
biosphere | the life-support system of the Earth biota: living things |
atmosphere | the layer of gases around the Earth |
lithosphere | the outermost layer of the Earth; includes the crust and uppermost part of the mantle |
hydrosphere | the water on the Earth's surface |
Sustainable ecosystems | ecosystems that are diverse and provide for the needs of the organisms that live there |