Constellations: The Patterns in our Sky

Hi, I’m Marley, the astronomer here at the Space Centre.

Something we talk about a lot here are the constellations and asterisms we see in the night sky. If I asked you to think of a constellation, you might think of the Big and Little Dippers. Those two patterns are actually something called an asterism. Constellations have formal boundaries, kind of like borders, in the sky. An asterism is a star pattern that is not strictly defined. The stars that make up an asterism could be contained within a constellation, like how the Big Dipper is part of Ursa Major. Asterisms can also be made up of stars that come from different constellations entirely. One you can see in Vancouver now is the Summer Triangle asterism, which is made up of the brightest stars from the constellations Aquila, Cygnus, and Lyra.

How do astronomers define a constellation? The International Astronomical Union (IAU), the recognized authority for assigning designations and names to celestial bodies, defines a constellation as an area of the sky surrounded by its boundary. In 1922, the IAU agreed on a list of 88 constellations covering the entire sky, and by 1930 the boundaries of the officially recognized constellations were published. Of the 88, 42 are animals, 29 are inanimate objects, and 17 are humans or mythological creatures.

The ones that we tend to be most familiar with are the constellations that concern the humans or mythological creatures. They come from the ancient Greeks, and were listed by the astronomer Ptolemy. Constellations like Orion, Perseus, or Ursa Major are ones that you might be familiar with. However, the ancient Greeks were not the only people to come up with constellations.

People have been assigning importance to objects in the sky since they started to look up. Cultures around the world have used astronomy for navigation, agriculture, and religious or other cultural reasons. The patterns or images seen in a part of the sky are different from group to group. Nadieh Bremer, an astronomer and data visualization artist, created an interactive visual tool called Figures in the Sky. It shows you some of the constellations from different cultures across the world, which gives you another perspective of what others see in the stars.

Unfortunately, knowledge about what constellations would have been seen by people thousands of years ago have been lost, and at times intentionally. I am from Calgary, which is on the traditional lands of the people of the Treaty 7 region. This includes the Blackfoot Confederacy (comprised of the Siksika, the Piikani, and the Kainai First Nations), the Tsuut’ina First Nation, the Stoney Nakoda (including Chiniki, Bearspaw, and Goodstoney First Nations), and is also home to the Métis Nation of Alberta Region 3. Indigenous peoples of Canada have their own constellations, each with their own meanings and importance. The Rothney Astrophysical Observatory has a resource on traditional Indigenous sky stories from the Siksika of the Blackfoot and the Ininewuk of the Cree that you can use to begin to learn about different view of the night sky.

Now, living on the unceded ancestral territories of the xʷməθkʷəy̓əm (Musqueam), sḵwx̱wú7mesh (Squamish) and sel̓íl̓witulh (Tsleil-Waututh) First Nations, I have the opportunity to learn all about a different view of the night sky.