Knowra Galaxy morphology Galaxy morphology Galaxy morphology classifies galaxies by visible shape and structure, including their disks, central bulges, bars, spiral arms, and irregular features.
Hubble sequence : A classification scheme that arranges galaxies by broad visual form, from ellipticals through spirals to irregulars. It provides the best-known framework for sorting galaxies by appearance.
Galaxy disk : A flattened, rotating component of a galaxy containing stars, gas, and dust. Its orientation and structure largely determine a galaxy's apparent shape.
Galaxy evolution : The changes in galaxies' properties and structures over cosmic time. Morphological populations reveal how galaxy structures change across cosmic history.
Galaxy kinematics : The study of motions of stars, gas, and other matter within galaxies. Kinematics measures motion directly, while morphology classifies visible form.
Edwin Hubble : An American astronomer who established the extragalactic nature of spiral nebulae and devised a galaxy classification scheme. His scheme gave galaxy morphology its enduring visual sequence.
Elliptical galaxy : A galaxy with a smooth, ellipsoidal appearance and little visible disk structure. Ellipticals occupy one major branch of the Hubble sequence.
Galaxy bulge : A dense, roughly spheroidal concentration of stars at the center of many disk galaxies. Bulge prominence helps distinguish morphological types.
Galaxy interaction : A gravitational encounter between galaxies that can distort their shapes and redistribute their matter. Tidal distortions and mergers produce recognizable morphological features.
Galaxy photometry : The measurement of light received from galaxies, including its brightness and distribution. Photometry quantifies image structure that visual morphology describes by type.
Hubble tuning-fork diagram : A diagram organizing elliptical and disk galaxies into a branching visual classification. It depicts the classic scheme underlying many morphological labels.
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