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What Is A Galaxy
Before, humans believed that there was only one galaxy in this universe, the milky way galaxy. At present, it’s known that there are two trillion galaxies in this universe. In this article, we’ll get an explanation of the types of galaxies.
The Galaxy
Galaxies are a collection of dust, gas, and stars that come together with the help of gravity. A small galaxy contains around a few hundred million stars, and the largest one contains approximately one hundred trillion stars. Galaxies are segmented into four different types:
- Irregular
- Spiral
- Peculiar
- Elliptical
Irregular
The irregular galaxy is unique and completely different from the others. These tend to be dwarf, small, and lack any particular shape or size as normal or regular. The Milky Way galaxy has many irregular satellite galaxies. They don’t have any components like bulges, arms, discs, etc. Out of many irregular-shaped galaxies, the most famous is the Large Magellanic Cloud.
NASA has shown that irregular galaxies are different from others because of the past interactions with neighbouring galaxies. Also, the dust abundant in this galaxy makes the visibility of stars very difficult, making this galaxy unique. It is differentiated into two types:
- IrrI (Irr1)
- IrrII (Irr2)
This IrrI has plenty of young stars and an abundance of hydrogen gas.
Spiral
The spiral Galaxy is one of the most common in this universe. You can easily identify a spiral galaxy by its flat, wide disks of dust and rotating gas. Some spirals are bound tightly, while others have wide-flung arms. Out of millions of present galaxies, 77% are spiral galaxies. The Milky Way galaxy is also a spiral galaxy. It rotates at a speed of 168 miles per second.
We differentiate these galaxies into three components.
- Bulge
- Disk
- Halo
Bulged one is spherically shaped and only has old stars. The shape of the galaxy is by disc component. Here new stars are born in the arms of the disc. When arms are absent, it’s called S0 or lenticular. The Halo components are located around the outer edge. Just like a bulged component, the halo consists of old stars called globular clusters.
Standard or regular spiral galaxies, denoted as S or SA. These notations refer to the tightness of the spiral. These are generally letters like ‘a’ ‘b’ ‘c’ ‘d’, and this continues. Here ‘a’ shows the tightest spiral.
Peculiar
Peculiar galaxies are a result of galactic collisions. These collisions are not always action-packed. These galaxies compose around 5-10 percent of all present galaxies. Thus, we can say that these collisions commonly occur in this universe.
Elliptical
The name elliptical galaxy is due to its lack of overall structure and oblong shape. Some of these are spherical, while the rest of them are cigar-shaped. The size of the elliptical galaxy ranges from a few light-years to being larger than the milky way galaxy. Scientists are not clear about the formation of the elliptical galaxies. Thus, they assume these are also a result of galactic collisions.
Naked Eye Galaxy
Some galaxies are clearly visible with naked eyes due to their brightness. This means you do not need any source like binoculars or a telescope to look at them. Sometimes the pollution tends to spoil the view. Here are a few brightest galaxies that you can observe in a clean moonless environment with your naked eye.
- Andromeda Galaxy, it has 3.4 magnitudes.
- Large Magellanic Cloud has a magnitude of 0.9
- Triangulum Galaxy has a magnitude of 5.7
- Small Magellanic Cloud has a magnitude of 2.7
- Sculptor Galaxy has a magnitude of 7.2
- Bode’s Galaxy has a magnitude of 6.94
- Centaurus A has a magnitude of 6.84
Conclusion
The Milky Way is a barred spiral galaxy. The Antennae Galaxies are an example of colliding galaxies. The Andromeda Galaxy is set to collide with us in about 3.75 billion years. The galaxies you’ll find in space are milky way galaxies, planets, meteoroids, black holes, and quasars. We are here to decode the unknown for you. The universe is vast and unknown, but we have some explanations which explain some unknown phenomena and these explanations on the types of galaxies do explain a lot of these unknowns.
