Galaxies

Types of Galaxies

Scientists classify all galaxies into three major categories: elliptical, spiral and irregular. About two-thirds, including the Milky Way, are spiral shaped. Their sizes range from millions of stars, gas, and dust clouds to more than a trillion, all held together with gravity.

• Spiral Galaxies are the most recognizable type. They have a clear spherical center, and the arms have a spiral structure, extending outwards. Another sub-type are Barred Spiral Galaxies and are similar to traditional spiral galaxies, but their core is shaped like a bar. These bars are believed to be short-lived with the core of the galaxy eventually rounding itself out.
• Elliptical Galaxies are spherical orbs, often elongated in shape and show no detail whatsoever when imaged. They are often found in galaxy clusters.

• Irregular galaxies do not have a distinct shape like spiral or elliptical galaxies. About one fourth of all discovered galaxies are irregular. A great example of an irregular galaxy is the Cigar Galaxy (M82).