Constellations and Asterisms
What are they? Simply put, they are our Earth-based interpretation of star patterns in the sky.
The ancient Greeks attributed mythical characters to many of the constellations we know today, and the brightest stars in a constellation are normally given Greek alphabet letters. The star names, on the other hand, are mainly Arabic.
Every culture around the world has created their own stories and legends about the shapes they saw in the sky. In 1930 the International Astronomical Union set official boundaries on groups of stars and recognised 88 constellations across the north & south hemispheres.
Asterisms are smaller groups of stars that may be part of one or more constellations. They are typically well known groups such as The Plough (part of Ursa Major) or The Summer Triangle (a combination of stars in three different constellations).
Test your knowledge on some of the popular constellations with our Constellation Art download.
Constellations
Learn to spot the best known constellations in the sky, identifying their shapes with our constellation drawings.
Take a good look at the shape and pattern of the stars and see if you can identify the same shape in the sky at night. Can you see more stars or less stars? The more stars you see in the constellation, the less light pollution you have in your area (and the darker your skies are).
Trace the pattern of the constellation and add your own artwork to develop the mythical character. Why not make your own story about the constellations you see?
For example, when Orion rises over the Ballycroy skies in Winter, we like to think of him as representing our own legendary giant – Daithí Bán. Who knows what stories are ancestors here created when they saw this giant in the night sky?
Let your imagination wander as you learn about the patterns of stars forming constellations and the legends and myths that have been attached to them over thousands of years.
Ursa Major
When can you view? All year round in the northern skies. Ursa Major is Latin for ‘Great Bear’. It also contains the famous asterism known as ‘The Plough’ or ‘Big Dipper’ containing seven stars – two of them (called ‘the Pointers’) point the way to the North Star (Polaris).
Mythology – There are both Greek and Roman myths about Ursa Major. A Roman myth involves Ursa Major and the nearby constellation of Ursa Minor (the ‘Little Bear’).
A beautiful maiden, Callisto, was hunting in the forest, but grew tired and laid down to rest. The god Jupiter noticed her and was smitten with her beauty, which made his wife, Juno, extremely jealous, so she turned Callisto into a bear. Some time later, Callisto’s son, Arcas was also turned into a bear. To protect both mother and son, Jupiter took both bears by their tails and swung them up into the heavens to live there forever – this explains the length of the tails, which are much longer than usual!
Cassiopeia
When can you view? – All year round and known as a circumpolar constellation (i.e. it circles the North Pole star.)
Mythology – In mythology Cassiopeia is the vain and boastful Queen of Ethiopia and wife of ancient King Cepheus. She insulted the Nereids (sea nymphs) by boasting she was more beautiful than they. To avenge the insulted Nereids, Poseidon, god of the sea, sent Cetus the whale monster. Cassiopeia chained her daughter Andromeda to a rock as a sacrifice for the monster. Fortunately the hero Perseus rescued her on his way home from slaying Medusa.
Leo
When can you view? – In spring skies this is a familiar constellation. Look out for the ‘backwards question mark’ to help identify the head of the Lion. The bright star at the bottom of the figure is known as Regulus.
Mythology – Leo is known as a Lion across many cultures. It is also a constellation in the zodiacal calendar as the Sun moves through the constellation in the summer months. The Greeks believed that Leo represented the lion that stalked and devoured the people of Nemea. Its skin was said to be impervious to all weapons and no ordinary man could kill it. Hercules took on the task and was unable to pierce the skin of Leo but eventually used his great strength to choke the beast to death. He then skinned it with the lion’s own claws and donned the pelt.
Cygnus
When can you view? – Cygnus is a major constellation in the northern hemisphere summer skies. It is best viewed from June to November. Cygnus is easy to find as its cruciform shape is also known as the Northern Cross and appears to be flying down the middle of the Milky Way. Cygnus contains one of the brightest stars in the night sky – Deneb (also the corner star of the Summer Triangle asterism).
Mythology – Cygnus (the Swan) has been associated with several myths. A Greek myth is that Cygnus represents the bird into which Zeus (King of the Gods) transforms himself in order to seduce Leda, Queen of Sparta. Another myth is that Cygnus represents tragic Greek hero Orpheus, who was murdered for refusing to honour Dionysus. He was then transformed into a swan and placed in the sky.
Pegasus
When can you view? – Pegasus is best seen from August to October and can be easily identified by its four stars that form the “Giant Square of Pegasus”. The constellation Pegasus was listed by the Greek astronomer Ptolemy in the second century AD.
Mythology – Pegasus was known as the winged horse in Greek mythology. The Greek word “Pegazo” means “to spring forward” and legend says that Pegasus was created when the winged horse leapt from the neck of Medusa the gorgon when Perseus cut off her head. Other stories say Pegasus originates from Poseidon mixing the blood of Medusa in the sea to create a Pmagical pure white stallion in honour of his love.
Orion
When can you view? – During Winter and Spring
Mythology – In Greek mythology, Orion was a mighty giant and hunter who boasted that he could slay any creature on Earth. There are many legends of his special powers such as walking on water, and various stories of how he was killed.
One story is that Diana, the archer-goddess with whom Orion was a favourite, was tricked into firing the arrow that killed Orion. The story goes like this… Apollo, her jealous brother, observed the giant Orion wading through the sea with his head just above water and challenged Diana to hit the black island in the distance. Diana took fatal aim and discharged the arrow, killing her beloved Orion. As recompense, she then placed him among the stars as a giant along with his with sword, and his famous belt of stars.
Other points of interest – The three stars forming Orion’s belt are called “The Three Marys” in Spain, Portugal and South America. Those with good eyesight (or using binoculars), can make out that the middle “star” of Orion’s dagger is fuzzy – this is the famous Orion Nebula, a huge region of star formation, containing over 700 stars, and stretching more than two Moon diameters across the sky.