What do astronomers mean by a constellation?

There’s a lot of different things to understand about the night sky. With thousands of stars up there, it only makes sense that throughout history, people have looked up there and seen different images in their mind.

At it’s most basic, a constellation is simply a concept of the human minds imagination. But is this a good definition of a constellation, or is there a better one out there? Let’s look at what astronomers really mean when they call something a constellation.

What do astronomers mean by a constellation?

When astronomers refer to a constellation, they’re talking about a group of stars that together to form a recognizable pattern. Many of these patterns are related to mythology, however some of them are not, and are just named after particular objects.

There are 88 official constellations up there in the night sky, and all of them resemble a different shape, pattern, object or even a person. Not all of them actually look like their respective constellation, although you’ll probably be surprised just how closely some of them are to their name.


Around half of the constellations in our night sky were discovered in the writings of astronomer Ptolemy in the 2nd Century. He likely got these constellations from Ancient Greeks and Babylonians, so many of them date back thousands of years.

Other constellations may only date back a few hundred years, where seafaring navigators have discovered them on their travels. An example of this is the constellation Sculptor, which takes it’s name from the apparatus used by astronomers when looking at the night sky.

So the reality is that when astronomers talk about a constellation, they’re really just referring to a group of stars in the sky.

Common Questions about Constellations

Are there more than 88 constellations?

There are only 88 official constellations in the night sky. However, these are just the constellations that are recognized by the IAU (International Astronomical Union. Throughout time, many more constellations have been recognized by astronomers, and have eventually ended up being not used or adapted into other constellations. So, you might actually be able to see a figure of stars in the sky and give it your own constellation based on it’s shape!

What do astronomers use constellations for?

Astronomers generally use constellations as a tool to track down other stars, galaxies or objects in the night sky. They’re also quite useful for tracking any satellites that we’ve sent up into space, too.

What is the biggest constellation?

The biggest constellation in our night sky is Hydra, the Sea Serpent. It has a size of more than 1300 square degrees.

Are constellations permanent?

Throughout the year, the Earth moves around the Sun, so this positions that the constellations are in will be different. However, if we are comparing them year upon year, then constellations will stay pretty much the same for humans, as it takes thousands and millions of years for any real adjustments in their position to be made.

Why don’t constellations look like their names?

Constellations have taken their names from an individual who has named them, so of course they are subjective. However, there are definitely some constellations that look more like their constellation name than others, like Gemini. Some constellations don’t look as much like their name as others, but usually we can at least see a resemblance.


In conclusion, a constellation is just a group of stars above us in the night sky that when grouped together, forma resemblance to a person, shape, animal or object. There are 88 different constellations for us to discover in the night sky, however you cannot see all of them all the time due to the Earth’s inclination. In fact, some constellations are never visible in the Northern hemisphere, and vice versa for the Souther hemisphere too!

Leave a Comment