Author at ‘The Secrets Of The Universe’, I am a science student from Romania. I am also the founder of Astronomy Hub, an organization for popularizing astronomy and astrophysics. I love reading philosophy and literature, enjoy classical rock, blues, and watch movies.
Galaxies are cool. Everybody knows that. It is the place that keeps around billions of stars. It’s the place where stars like our Sun live, and where planets like Earth with people like us think and study the world. There are billions of galaxies in our Universe of different shapes and sizes. Everybody should know our 13.5 billion years-old Milky Way. Also, you may have heard of Andromeda or M31. It is the galaxy closest to us, our neighbor.
Actually, Andromeda likes the Milky Way so much it’s coming closer to it every day. They are really going to meet each other, in 4.5 billion years or so. So these are the most known galaxies, right? But what about the biggest? The “biggest of the big”? The name of that beast is IC 1101. As I said, galaxies come in all sizes. But to understand what sizes we are talking about, take some time and imagine it.
Understanding distances
If something is located 1 light-year away from us, it means that the light from it will reach us in one year. That means that if looking for an object one light-years away, we will always see it as it was one year ago. Light travels pretty fast. Somewhere around 300,000,000 m/s. The average speed of a car is 25 m/s. It means light travels 12 million times faster than a car.
Now think about our galaxy, whose diameter is 105,000 light-years. Sounds big. But the biggest we know about is estimated to be around 6 million light-years in diameter. That means that if you would look from one corner to the star on the opposite, it would take 6 million years for its light to reach you.
Actually, saying that IC 1101 is the largest galaxy in the Universe is not accurate. Considering how important accuracy is in the world of science, I am impressed by how much I see this mistake made. IC 1101 is the biggest galaxy discovered. It doesn’t mean there isn’t something bigger. It’s just that we didn’t see it yet.
Read More:
- Distances And Their Units In Astrophysics
- How do black holes and neutron stars form?
- Quasars: The Most Powerful Objects In The Universe
What types of galaxies exist?
IC 1101 is an elliptical galaxy. There are 3 major types of galaxies, subdivided then in some smaller ones. The author of this classification is the brilliant astronomer of the 1920s, Edwin Hubble. The 3 major types are elliptical, spiral, and irregular. Spiral galaxies are the most common in the Universe. The Milky Way or Andromeda are spiral galaxies. You can read more about the galaxies and their interactions in this article of our Basics of Astrophysics series.
These are also the galaxies with the youngest stars and which give birth to most of the stars. On the other hand, elliptical galaxies are much older and are home to old stars too. These elliptical galaxies are found largely in galaxy clusters and dust clouds. Now irregular galaxies, such as the Small Magellanic Cloud, are as their name suggests, irregular in shape. These are even older galaxies.
Using “candles”
So how was this 6 million light-years long elliptical galaxy discovered? Astronomers can calculate short distances easily, using a method called parallax. This works well for a lot of stars. But when talking about distances such as 6 million light-years, we use something different: we calculate their distance based on their brightness. But in such a calculation we would need something to compare it to. That is why we use “candles”, galaxies or stars that have become standard to us, we know their distance, and hence we compute the distance to other objects in the Universe.
IC 1101 was first discovered by William Herschel, in 1870 or so. It was first thought to be just a nebula. Everybody believed that until Hubble came in the 1920s and proved, with his new classification of galaxies, that IC 1101 is a galaxy: a big one actually.
So in a Universe with galaxies like IC 1101, it’s easy to feel small. In fact, some psychologists found out that the biggest feelings of insignificance and loneliness come from the people who came in contact with the Universe in some way.
Mostly, you can find these feelings at the observatory, that being the place where psychologists found their people. But instead of feeling small, and lonely, or insignificant, you may want to feel proud that you are part of such a beautiful species, that you live on such a nice planet, and most of all, that you can contemplate at who you are and why are you here.
