Hubble sequence

<p>The Hubble sequence is a <a href="/facts/Galaxy_morphological_classification/AGbMJ9Dp">morphological classification scheme</a> for <a href="/facts/Galaxy/zCyUvEf7">galaxies</a> published by <a href="/facts/Edwin_Hubble/fpX3JlbJ">Edwin Hubble</a> in 1926. It is often colloquially known as the Hubble tuning-fork diagram because the shape in which it is traditionally represented resembles a <a href="/facts/Tuning_fork/bN6mcXCH">tuning fork</a>.
It was invented by John Henry Reynolds and Sir James Jeans.
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<p>The tuning fork scheme divided regular galaxies into three broad classes – <a href="/facts/Elliptical_galaxy/1PUchrj1">ellipticals</a>, <a href="/facts/Lenticular_galaxy/UuG7XJYf">lenticulars</a> and <a href="/facts/Spiral_galaxy/hRT2dtxJ">spirals</a> – based on their visual appearance (originally on <a href="/facts/Photographic_plate/LbTmHKJb">photographic plates</a>). A fourth class contains galaxies with an <a href="/facts/Irregular_galaxy/P95rRpYR">irregular</a> appearance. The Hubble sequence is the most commonly used system for classifying galaxies, both in professional astronomical research and in <a href="/facts/Amateur_astronomy/lBgH19WH">amateur astronomy</a>.
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Hubble sequence open-in-new

Hubble sequence