How are spiral galaxies classified by astronomers?

Astronomer Edwin Hubble classified galaxies into four major types: spiral, barred spiral, elliptical and irregular. Most of the nearby, bright galaxies are ... Spiral galaxies have a variety of shapes and are classified according to the size of the bulge and the tightness and appearance of the arms. read more

Astronomer Edwin Hubble, after whom the space telescope is named, classified galaxies according to shape. The Hubble scale chart takes a wishbone, or tuning fork shape. Armless, elliptical galaxies are on the left. Spirals are divided into those with a central bar and those without one. Looser arm windings are toward the right. read more

Hubble Sequence classification of spirals relies essentially on two features: The tightness of their spiral arms, and whether or not it has a central elongated “bar” structure. This page may be out of date. read more

Spiral galaxies have a variety of shapes and are classified according to the size of the bulge and the tightness and appearance of the arms. The spiral arms, which wrap around the bulge, contain numerous young blue stars and lots of gas and dust. read more