Types of Galaxies Galaxies are the biggest groups of stars in the universe. They can contain anywhere from a few million to many billions of stars. Galaxies are divided into three types according to shape: spiral, elliptical, and irregular galaxies. - Spiral galaxies spin and appear as a rotating disk of stars and dust, with a bulge in the middle. Several spiral arms reach outward from the central bulge like the arms of a pinwheel. Spiral galaxies have lots of gas and dust. Most of their stars are young and blue in color. - Elliptical galaxies are more-or-less egg shaped. The... Show more Types of Galaxies Galaxies are the biggest groups of stars in the universe. They can contain anywhere from a few million to many billions of stars. Galaxies are divided into three types according to shape: spiral, elliptical, and irregular galaxies. - Spiral galaxies spin and appear as a rotating disk of stars and dust, with a bulge in the middle. Several spiral arms reach outward from the central bulge like the arms of a pinwheel. Spiral galaxies have lots of gas and dust. Most of their stars are young and blue in color. - Elliptical galaxies are more-or-less egg shaped. The smallest elliptical galaxies are as small as some globular clusters. The largest elliptical galaxies can contain over a trillion stars. Most stars in elliptical galaxies are reddish to yellowish in color because they are old stars. Most elliptical galaxies contain very little gas and dust because these particles have already formed into stars. - Irregular galaxies are neither elliptical nor spiral in shape. Most irregular galaxies were once spiral or elliptical galaxies that were then deformed. This may have happened by gravitational attraction to a larger galaxy or by collision with another galaxy. Dwarf galaxies are small galaxies containing only a few million or billion stars. Dwarf galaxies are the most common type of galaxies in the universe. However, because they are small, they are also dim, so we don’t see very many dwarf galaxies from Earth. Most dwarf galaxies are irregular in shape. However, there are also dwarf elliptical galaxies and dwarf spiral galaxies. Dwarf galaxies are often found near larger galaxies. They sometimes collide and merge with their larger neighbors. Show less
Types of Galaxies Galaxies are the biggest groups of stars in the universe. They can contain anywhere from a few million to many billions of stars. Galaxies are divided into three types according to shape: spiral, elliptical, and irregular galaxies. - Spiral galaxies spin and appear as a rotating disk of stars and dust, with a bulge in the middle. Several spiral arms reach outward from the central bulge like the arms of a pinwheel. Spiral galaxies have lots of gas and dust. Most of their stars are young and blue in color. - Elliptical galaxies are more-or-less egg shaped. The smallest elliptical galaxies are as small as some globular clusters. The largest elliptical galaxies can contain over a trillion stars. Most stars in elliptical galaxies are reddish to yellowish in color because they are old stars. Most elliptical galaxies contain very little gas and dust because these particles have already formed into stars. - Irregular galaxies are neither elliptical nor spiral in shape. Most irregular galaxies were once spiral or elliptical galaxies that were then deformed.
This may have happened by gravitational attraction to a larger galaxy or by collision with another galaxy. Dwarf galaxies are small galaxies containing only a few million or billion stars. Dwarf galaxies are the most common type of galaxies in the universe. However, because they are small, they are also dim, so we don’t see very many dwarf galaxies from Earth. Most dwarf galaxies are irregular in shape. However, there are also dwarf elliptical galaxies and dwarf spiral galaxies. Dwarf galaxies are often found near larger galaxies. They sometimes collide and merge with their larger neighbors.
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