If you are new to astronomy or love viewing the stars from the comfort of your own backyard, then it’s time to learn about circumpolar constellations.
There are many different constellations found in our night sky, but which ones you see every time you look up depends heavily on your location on Earth.
Circumpolar constellations are constellations that are found around one of the Earth’s poles all year round.
What that means is that there are certain constellations that are only visible in the Northern Hemisphere and some that are only visible in the Southern Hemisphere. They never dip below the horizon and are easily visible in our night sky.
Here we are going to take a look at the Northern Hemisphere’s circumpolar constellations including what they are and some really interesting facts about each one.
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Circumpolar Constellations: What Are They?
Constellations are groups of stars that we use to draw pictures in the night sky. Some constellations are renowned worldwide and divided into their own groups – and one such group is called circumpolar constellations.
Circumpolar constellations are very special constellations found in our night sky here on Earth. Unlike other constellations, they never rise and never set over the horizon as the Earth rotates during the night – they always remain above our heads all through the night while stargazing, going around in a great big circle.
This is because these circumpolar constellations rotate around a point known as the north celestial pole. The north celestial pole is the point where Earth’s axis of rotation can be found so it remains a fixed point in the sky that never changes.
To find the north celestial pole, just find Polaris. Polaris is a star known by many different names – including the North Star or the Pole Star. This is because Polaris sits so close to the north celestial pole in our Northern Hemisphere sky that it almost seems like the point of rotation.
Polaris can be found in the constellation of Ursa Minor (or its more familiar asterism, the Little Dipper) and sits at the end of its tail. You can easily find it in our night sky by finding the Big Dipper in Ursa Major, and following the two stars that make up the side of the cup of the Big Dipper in a straight line – there is Polaris, and the north celestial pole.
And the nearest constellations around this point are the circumpolar constellations of the Northern Hemisphere. While other constellations dip under and rise above the horizon, these constellations constantly stay above our heads.
What Are The Circumpolar Constellations Of The Northern Hemisphere?
There are nine circumpolar constellations overall, but only six can be seen in the Northern Hemisphere. These six circumpolar constellations in the Northern Hemisphere are Ursa Major, Ursa Minor, Draco, Camelopardalis, Cepheus, and Cassiopeia.
They are the six constellations that surround the star Polaris, so they are the closest constellations to the northern celestial pole. While they rotate with the sky in a giant circle, they never vanish from sight over the horizon. This means that on every clear night, we can look up and observe them all night long.
The other three can be found at the southern celestial pole in the Southern Hemisphere, so we cannot observe them from our backyards here in the Northern Hemisphere. However, the other remaining circumpolar constellations are Carina, Centaurus, and Crux.
So, let’s take a closer look at each of the circumpolar constellations of the Northern Hemisphere in a little more detail.
Ursa Minor
Let’s start with Ursa Minor as it is the closest circumpolar constellation to the northern celestial pole.
Ursa Minor is also known by a few alternative titles including the Little Bear, or Lesser Bear. It is also known as the asterism the Little Dipper, due to its close relation to Ursa Major or the Big Dipper.
It has been used for centuries in navigation due to its proximity to the northern celestial pole. It is the home constellation of Polaris, the North Star that is constantly used in navigation due to its fixed position in the night sky.
Polaris is also the brightest star in this constellation, with an apparent magnitude of 2.00, so it can be easily seen using the naked eye – making it the perfect star for sailors to use to guide their ships to their destinations.
However, despite its importance in navigation, Ursa Minor is not a particularly large constellation. It is the 56th largest constellation and occupies an area of 256 square degrees. It is situated in the third quadrant of the Northern Hemispheres, between the +90 degrees and -10 degrees latitudes.
It also contains four other named stars (as approved by the International Astronomical Union) are Baekdu, Kochab, Pherkad, and Yildun. Altogether, there are seven important stars that make this constellation.
As for the mythology behind Ursa Minor, there are two main Greek myths most commonly associated with this constellation.
One myth claims that Ursa Minor represents one of the nymphs that took care of Zeus and raised him away from his father Cronus, the titan who ate all of his offspring in fear that one of them would overthrow him. Zeus was hidden away by his mother and raised in secret until he could grow up and dethrone his father.
The other myth is the myth of Callisto. Callisto was a nymph who swore a vow of chastity to the virgin goddess Artemis and became one of her many huntress companions. However, her vow was broken (either willingly or unwillingly) and she bore a child with Zeus named Arcas.
For breaking her vow, Callisto was changed into a bear and one day was almost killed by her now adult son, but Zeus intervened and lifted the two to the Heavens to become Ursa Minor and Ursa Major. So, Ursa Minor represents Arcas.
Ursa Major
Ursa Major is the closest constellation to Ursa Minor and the two are very closely connected in more than just area.
Where Ursa Minor is the little bear, Ursa Major is known as the Great Bear or Larger Bear. It is the largest constellation in the Northern Hemisphere and the third largest in the night sky. It is also renowned for containing the astermin, the Big Dipper, which while not a constellation in itself, is still one of the most easily recognizable groups of stars.
Because of its large size which takes up 1280 square degrees of area, Ursa Major also contains a lot of different stars in its constellation. Twenty-two of them are named but its brightest star is Alioth, which boasts an apparent magnitude of 1.76.
Two other important stars to note are Dubhe and Merak – these are the two stars that form the far side of the bowl of the Big Dipper and form an imaginary line that leads directly to Polaris and the northern celestial pole.
Ursa Major is one of the most well-known constellations in the Northern Hemisphere due to its size and popular asterism, the Big Dipper. It is even mentioned in the Bible, showing just how well-known and discussed this constellation is and has been for thousands of years.
The mythology behind Ursa Major is closely connected to Ursa Minor. It represents Callisto, the nymph whose vow of chastity to the virgin goddess Artemis was broken when she bore a son. She was then turned into a bear, either by Zeus to hide her from his wife Hera’s wrath or by Artemis herself as punishment for breaking her vow of chastity.
Either way, Callisto was turned into a bear and spent years roaming the wild under constant threat of being hunted. She finally came face to face with her son, Arcas, and the two nearly killed one another until Zeus lifted them both to the Heavens.
There is an alternative myth that claims that Ursa Major represents Adrasteia, one of the nymphs who cared for Zeus and raised him away from his father Cronus. Once Zeus overthrew his tyrannical father, he paid homage to the nymphs who had raised him in safety by placing constellations in the sky to represent them.
Draco
Snaking its way between Ursa Major and Ursa Minor is the constellation of Draco.
Draco is also known as the Dragon and is a constellation made of a string of stars that represent a long, serpent-like body. At its end, a few stars are clustered together to represent the head, hence why this constellation was often associated with dragons and serpents.
It is linked to one of the most well-known Greek myths – the twelve labors of Heracles. Draco is meant to represent the dragon Ladon, who protected the golden apples in the garden of Hesperides.
Heracles was tasked with stealing some of these golden apples and had to kill Ladon in order to complete his labor. The goddess Hera, who was the owner of the apples, placed Ladon’s image in the sky as a constellation in homage of his service.
Nearby, the constellation of Hercules can also be found but this constellation is not a circumpolar one, while Draco is.
Draco is one of the largest constellations in our night sky and takes up 1083 square degrees of area. It can be seen at latitudes between +90 degrees and -15 degrees, taking up a lot of space in the third quadrant of the Northern Hemisphere.
Its brightest star is Gamma Draconis (also known as Eltanin), which has an apparent magnitude of 2.3617, but is made up of 17 named stars in total.
Camelopardalis
Camelopardalis is one of the lesser known constellations despite its proximity to many other famous constellations. It is also known as the Giraffe as its formation is very similar to the long neck of a giraffe with a cluster of stars representing its body.
Unlike other constellations which have been named and discussed during ancient times, Camelopardalis was not created until 1624 by a Dutch astronomer.
It is a fairly faint constellation (it’s brightest star is Beta Camelopardalis which only has an apparent magnitude of 4.03, making it barely visible to the naked eye) and so, it does not have any in-depth mythology surrounding its name.
It does contain an asterism in the form of Kemle’s Cascade – a straight line formed in the sky by more than 20 stars – but Camelopardalis is one of the least exciting constellations. It occupies an area of 757 square degrees and is found in the second quadrant of the Northern Hemisphere, so it is not particularly large or bright.
However, it is a circumpolar constellation so it has secured its place in this guide.
Cepheus
Cephus is a circumpolar constellation that is named after a king from Greek mythology.
King Cepheus was the king of Aethiopia and was descended from one of Zeus’ lovers, Io. He is mainly associated with the myth of Perseus as he was married to Cassiopeia, a vain woman who boasted about her own beauty and compared herself to the nymphs of the sea.
This angered the sea god Poseidon, who sent a sea monster to plague Cepheus’s kingdom. When Cepheus sought advice to stop the sea monster, he was told he had to sacrifice his daughter Andromeda to the monster in order to appease Poseidon.
Andromeda was then tied to a rock but was rescued by the hero Perseus, who then defeated the sea monster and married Andromeda.
A fight broke out at the wedding between Perseus and another potential suitor of Andromeda and when Perseus used the head of Medusa to turn his rival to stone, Cephus and Cassiopeia unfortunately were turned to stone too as they did not look away in time.
Because of this, Cephus can be found nearby the constellation of Perseus and the constellation of his wife, Cassiopeia. However, only Cephus and Cassiopeia are circumpolar constellations as they never dip beneath the horizon during their rotation.
Cephus is not a very large constellation as it only takes up 588 square degrees of space. It can be found in the fourth quadrant of the Northern Hemisphere between the latitudes +90 degrees and -10 degrees. It is made of four named stars, the brightest of which is Alderamin which has an apparent magnitude of 2.514.
Cassiopeia
The final circumpolar constellation of the Northern Hemisphere is Cassiopeia.
Cassiopeia is named after the vain Queen of Aethiopia whose bragging nearly brought on the demise of her daughter and destruction of her kingdom. She was later turned to stone by Perseus by accident but takes her place in the constellations along with many noticeable features from that Greek myth.
The constellation Cassiopeia can be found in the first quadrant of the Northern Hemisphere between the latitudes of +90 degrees and -20 degrees, near to the constellations that represent her husband Cephus and her daughter Andromeda. This constellation is made up of eight named stars, the brightest being Schedar, with an apparent magnitude of 2.24.
Conclusion
Circumpolar constellations are some of the most observed in the world due to the fact that they never dip below the horizon.
Due to their consistency, many backyard astronomers and stargazers are able to view these constellations from their own home and some can even be clearly seen without the need of a telescope.
So, using the positions and guidance given above, why not step outside during the next clear night and observe these circumpolar constellations? Observing them is a rite of passage for backyard astronomers everywhere, so grab your telescope and get out there!
