Hubble classification system
A system developed by Edwin Hubble in 1936 that classifies galaxies as elliptical, spiral, barred spiral, lenticular, and irregular. Hubble speculated that galaxies might fit into an evolutionary sequence from earlier elliptical galaxies to later spiral forms, but most astronomers no longer believe this is the case. Our galaxy, the Milky Way, is a spiral galaxy. Also called Hubble sequence
The American Heritage® Science Dictionary
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