10 Irregular Galaxy Facts You Should Know

Whilst many people are aware of the other types of galaxy in our universe, some people aren’t aware of the irregular galaxy and what it actually is. It is named as such because it doesn’t take a strict shape like spiral galaxies, barred spiral galaxies or elliptical galaxies do. The large and small Magellanic clouds are probably the best examples of this galaxy type. 


However, they make up some of the brightest galaxies in the sky due to their abundance of stars. Let’s look at some facts about irregular galaxies.

Irregular Galaxy Facts

  1. Irregular galaxies are known for the strange shape they take, as they have no central bulge or spiral.
  2. Irregular galaxies are on average, some of the youngest in our universe. They’re typically between 4 and 8 billion years old, whereas other galaxies are as old as 12 billion years old. 
  3. It’s said that irregular galaxies are the result of collisions or mergers between two galaxies, with the result being a distorted irregular galaxy.
  4. There are three different types or further classifications of irregular galaxies.
  5. Because irregular galaxies take on no shape, it’s difficult to measure them, however on average they are approximately 20,000 light years in diameter.
  6. In our night sky, it’s estimated that as many as 20% of viewable galaxies can be classified as irregular.
  7. There are many different example of irregular galaxies. One of these is a dwarf irregular galaxy named IC 4710 , found in the constellation Pavo.
  8. The majority of irregular galaxies are very bright, which is a result of the gas and dust in them.
  9. This gas and dust means that many stars are formed within an irregular galaxy, giving them their brightness. 
  10. Because of their small size, these types of galaxy are in danger of crashing into large galaxies.
  11. When it comes to star formation, an irregular galaxy isn’t necessarily smaller than a spiral galaxy. In fact, they can actually match them when it comes to size.

Types of Irregular Galaxy

Although irregular galaxies are thought to be a catch-all name for anything that isn’t a spiral or ellipse, we can still further classify these irregular galaxies. We generally split them into three different categories based on their distinct shape, which is a little different that what your regular shape may be. 


We divide them into three main types. Firstly, there is the lrr l type – these are galaxies which actually have some structure, but not enough to be an elliptical or spiral. Secondly there is lrr ll, which means that it has no structure at all. And finally there is dlrr, are dwarf irregular galaxies are some of the earliest in our universe.


Common Questions about Irregular Galaxies

What is the best example of an irregular galaxy?

If you’re wondering what the most well known irregular galaxies are, then I’d say most people would probably look at the Magellanic clouds. There are two irregular galaxies, called the Large Magellanic and the Small Magellanic. However, in recent years the classification of the Large Magellanic has been much talked about, as they may actually be a different classification altogether.


Where are irregular galaxies found?

The majority of irregular galaxies are found in groups or large clusters. This is one of the reasons why this type of galaxy is in danger of colliding with others, because they are in such a tight proximity from one another.

What shape is an irregular galaxy?

Whilst spiral and elliptical galaxies are named after their shape, the whole point of the irregular classification is that these types of galaxies generally do not have a shape, and therefore cannot fit into any other classification.


How big is an irregular galaxy?

There is no strict size limits for an irregular galaxy. They average at 20,000 light years in diameter, and they make up some of the smallest galaxies in our universe. This leads astronomers to think they’re probably the result of collisions between other galaxies.

What type of galaxy do we live in?

We live in the Milky Way, which isn’t an irregular galaxy. It is actually a barred spiral galaxy, and one of the earliest galaxies in the universe.


In conclusion, the irregular galaxy is often looked over as other galaxies that have formed a structure are much more interesting to astronomers. However, their origination and composition is still of great interest. Hopefully this has helped you learn a little bit about irregular galaxies.


1 thought on “10 Irregular Galaxy Facts You Should Know”

  1. This really helped me a lot. I had a project, and I didn’t know nothing about galaxies but that to this I learned so much. Thank you for a helping an 8th grader that sucks at science. ?


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