What are Galaxies classified by?
1 Answer
Galaxies are classified into four major types: spiral, barred spiral, elliptical and irregular.
Explanation:
Galaxies are classified into four major types: spiral, barred spiral, elliptical and irregular.
Spiral galaxies have a variety of shapes and are classified according to the size of their bulge and tightness and appearance of its spiral arms.
The spiral arms, which are wrapped around the bulge, contain numerous young stars and lots of gas and dust. Stars in the bulge are older and redder. Yellow stars like our Sun are found throughout the disk of a spiral galaxy.
Barred spiral galaxies are spiral galaxies that have a bar-shaped collection of stars running across the center of the galaxy.
Elliptical galaxies do not have a disk or arms. Instead, they have a smooth, oval-shaped appearance. They contain old stars, and possess little gas or dust.
Irregular galaxies have neither spiral nor elliptical shape. They tend to be smaller objects without definite shape, and tend to have very hot newer stars mixed with lots of gas and dust.
Most of the nearby, bright galaxies are spirals, barred spirals or ellipticals.
