Types of Galaxies – 12 Known Types and Names of Galaxies
The Earth we live on is one of the many planets in the vast Solar System. The Solar System consists of planets, moons, comets, asteroids, and millions of stars, all part of a galaxy. But our galaxy isn’t the only one in the universe. In fact, there are countless galaxies, although our current understanding is limited to hundreds. With advancements in astronomy, we’ve identified and named many galaxies.
What is a Galaxy?
A galaxy is an enormous collection of stars, planets, gas clouds, and cosmic dust. These stellar systems are vast and consist of different types of stars, some of which are organized in clusters or spread out across the galactic plane. A key point to remember is that Earth is not classified as a star, as it doesn’t produce its own light.
Our Solar System revolves around the Sun, with all planets, including Earth, moving within the Milky Way Galaxy. Therefore, all life on Earth resides within the Milky Way.
Galaxies are not just made up of stars; they also contain other cosmic materials like nebulae, comets, and cosmic dust. Some of these stars are red or white dwarfs, and because of the immense distances between them, space appears largely empty. However, there are regions where stars cluster so closely that they give the appearance of cosmic fog or nebulas when observed from afar.
Characteristics of a Galaxy
A galaxy possesses distinct characteristics that set it apart from other cosmic phenomena. Here are a few features that define galaxies:
- Galaxies emit their own light rather than reflecting it. This light is often accompanied by an absorption spectrum, indicating the presence of gases around the stellar core.
- Galaxies typically have a defined shape and a bright central core, making them identifiable.
- Regardless of the distance from our solar system, galaxies are observable beyond the dark void of space.
Types of Galaxies
Galaxies can be classified into several categories based on their shapes and characteristics:
1. Spiral Galaxy
The most well-known type, spiral galaxies, have a distinct bulge at the center surrounded by spiral arms. These galaxies contain both old and young stars, and their fast rotation creates a flattened disk. The Milky Way, Andromeda (M31), and Whirlpool (M51) are examples of spiral galaxies.
2. Elliptical Galaxy
Elliptical galaxies range in shape from nearly spherical to elongated ellipses. They have a smooth, featureless appearance due to the even distribution of stars. These galaxies tend to contain older stars and less interstellar material. Examples include M32, M49, and M59.
3. Irregular Galaxy
Irregular galaxies lack a defined shape and can appear chaotic. Some irregular galaxies, like the Large Magellanic Cloud, are relatively small compared to typical galaxies. They often contain young stars and interstellar matter. Other examples include M110 and the Small Magellanic Cloud.
4. Lenticular Galaxy
Lenticular galaxies are a blend of elliptical and spiral galaxies. They have a central bulge like spiral galaxies but lack spiral arms. An example is NGC 5866.
Names of Known Galaxies
Here are a few well-known galaxies across the universe:
Milky Way Galaxy
Our home galaxy, the Milky Way, is a barred spiral galaxy containing billions of stars, planets, and other celestial bodies. It has a bright central core that is best observed in infrared and radio wavelengths due to dust and gas obstructing visible light.
Andromeda Galaxy
The Andromeda Galaxy is the nearest spiral galaxy to the Milky Way, located about 2.5 million light-years away. Also known as M31, it’s visible to the naked eye from Earth.
Large and Small Magellanic Clouds
These two irregular galaxies are satellite galaxies of the Milky Way, located about 150,000 light-years away. They are named after Ferdinand Magellan, the explorer who first recorded their existence.
Sombrero Galaxy
Named for its sombrero-like appearance, this spiral galaxy (M104) is approximately 28 million light-years from Earth. Its bright core is surrounded by a large bulge, possibly housing a supermassive black hole.
Rose Galaxy
This unusual galaxy, also known as UGC 1810, has a shape reminiscent of a rose. It’s part of a pair of interacting galaxies, with the smaller galaxy (UGC 1813) likely causing the distinctive spiral pattern.
Sculptor Galaxy
NGC 253, or the Sculptor Galaxy, is a dust-rich spiral galaxy located about 8 million light-years away. It is one of the brightest galaxies visible from Earth.
Black Eye Galaxy
This galaxy gets its name from a dark band of dust in front of its bright nucleus. The Black Eye Galaxy is thought to have formed through a collision with another galaxy.
Blue Wheel Galaxy
This galaxy is shaped like a blue wheel and is located about 2 million light-years away from Earth. It’s close enough to be observed with binoculars.
Cartwheel Galaxy
The Cartwheel Galaxy has a distinctive ring shape, possibly formed after a collision with another galaxy. It is located about 500 million light-years from Earth in the Sculptor constellation.
Sunflower Galaxy
Messier 63, or the Sunflower Galaxy, has spiral arms that resemble the pattern of a sunflower. It is located in the constellation Canes Venatici, around 27 million light-years away.
M101 (Ursa Major Galaxy)
Also known as the Big Dipper Galaxy, this spiral galaxy serves as a navigational reference for sailors and is located near the North Pole.
Whirlpool Galaxy
This galaxy, M51, has a striking spiral shape, and its structure is often studied by astronomers. It’s approximately 23 million light-years away from Earth.
Read More: Parallel Universes: How to Embrace the Concept of a Multiverse?
