The Cassiopeia Constellation – Facts in brief:
What is it?
Cassiopeia means ‘Queen of Ethiopia’, as she was married to King Cepheus of Ethiopia, in Greek mythology. The Cassiopeia Constellation is one of the oldest known constellations, and ranks as the 25th largest Constellation as one of the original 48 Constellations listed by Greek Astronomer Ptolemy, in the 2nd century.
It is one of the official IAU listed 88 modern constellations as seen in the night sky from Earth.
Cassiopeia (its Latin name) is quite easy to recognize, as it clearly resembles the outline of a large letter W shape, which is supposed to be the outline of the seated queen Cassiopeia.
The Cassiopeia Constellation is part of the Perseus family of Constellations.
Fellow Perseus family members include:
According to Greek mythology this constellation was named after a boastful and vain queen called Cassiopeia, who was the wife of King Cepheus.
Where is it located?
The Constellation of Cassiopeia is positioned in the first quadrant of the Northern Hemisphere, north of the celestial equator. It is sometimes referred to as being located in the NQ1 Quadrant.
FACT: The ecliptic is the imaginary line tracing the route that The Sun, the Moon, and the Planets take across the sky over the year.
Where can it be seen?
Co-ordinates of a right ascension, or left ascension and their declination are used to locate all of the Constellations, like Cassiopeia.
Cassiopeia is visible all year in the Northern Hemisphere and in some northerly parts of the Southern Hemisphere in the late Spring
The Stars of Cassiopeia can be clearly observed from Earth in the Northern Hemisphere in November and December, at around 22.00 hours in a northerly direction and visible for a few hours.
The Constellation of Cassiopeia lies at 1-hour right ascension and the Declination of Cassiopeia is 60 degrees north
It’s visible in the Northern Hemisphere at latitudes between +90 degrees and – 20 degrees and covers an area of 598 square degrees in the Northern sky.
The Cassiopeia Constellation is bordered by several other Constellations
Cassiopeia is around 441 light years from Earth with a magnitude of +3.38. (Approximately 720 times more luminous than the Sun) It’s a single, blue-white B-Type giant star.
How can you identify Cassiopeia?
The simplest method for spotting any particular Constellation from Earth is to first of all locate the brightest star in that Constellation, and then look at the neighboring illuminations, to see if you can identify a recognizable pattern.
Cassiopeia is visible as a large W shape in the night sky representing the arrogant and vane queen Cassiopeia spinning on her throne.
Cassiopeiais a Constellation that can be identified by locating its 5 brightest stars, which form a prominent W shape asterism.
The bright stars of Cassiopeia can be viewed from Earth, from a northern location, by the naked eye.
The Star System within Cassiopeia
The brightest star in Constellation Cassiopeia is called Schedar (Alpha Cassiopeiae).
The Constellation of Pegasus is easiest to identify in the Northern sky by identifying the asterism of 5 bright stars in the shape of the letter W.
The 5 bright stars that form the W shape, located from left to right are:
- Segin (Epsilon Cassiopeiae)
- Ruchbah (Delta Cassiopeiae)
- Y Cas (Gamma Cassiopeiae)
- Schedar (Alpha Cassiopeiae)
- Caph (Beta Cassiopeiae)
There are 8 named Stars within Cassiopeia that have been approved by the International Astronomical Union (IAU):
Cassiopeia A (Cas A) is a supernova remnant, found within the constellation, that’sabout 10 light years in diameter, and lies around 11,000 light years from Earth. It is not visible by naked eye.
Gamma Cassiopeiae (y Cas), also known as Navi, is one of the 4 brightest stars in the Cassiopeia Constellation with a magnitude that ranges from +0.6 – +3.0)
FACT: It is the combined light of the various bright stars in the star system that produces enough light to give Alpha Cassiopeiae (Schedar) the brightest star status in the Constellation of Cassiopeia.
Spotting Cassiopeia in the night sky
Cassiopeia is the 25th largest constellation.
The easiest way to spot the Constellation of Cassiopeia would be to locate the asterism collection of 5 stars and join the dots to form the shape of the letter W.
This simple technique of joining the dots represented by stars in the night sky can be used to spot other Constellation patterns too like the Question Mark or other mythical creatures from Greek mythology.
Location of Cassiopeia
The Constellation Cassiopeia is surrounded by various recognizable Constellations, in alphabetical order: Andromeda, Camelopardalis, Cepheus, Lacerta, and Perseus.
Cassiopeia can be spotted in the Northern Hemisphere, also referred to as the Northern sky.
The W asterism is a well-known guide-point in the sky used by astronomers and amateur stargazers to identify certain Deep Sky objects; like the neighboring Andromeda Galaxy.
When to see the Constellation Cassiopeia
The best months to spot the Constellation of Cassiopeia, the in the Northern Hemisphere is from November and December.
The best time of day to spot it is around 21.00 at night (22.00 Daylight Saving Time) local time around the world.
How was it formed, found and named?
Constellation in the sky and one of the 88 Constellation listed in the official IAU chart published by the International Astronomical Union (IAU). It fills an area of 598 square degrees.
- Initially, the shapes of their star patterns informally categorized the Constellations in the sky.
- Eventually, the IAU published the official listing of constellation boundaries. This maps the constellations by their sky coordinates not by the line patterns and shapes they are referred to by.
What’s within it?
There are many different Stars and Deep Sky Objects within the Cassiopeia Constellation.
The Cassiopeia Constellation contains:
- Eight main stars
- Three stars with confirmed planets
- Two Messier Objects (Messier 103, (M103, also referred to as NGC 581), and Messier 52, (M53, also referred to as NGC 7654)
- One associated meteor shower known as the ‘Perseid Meteor Shower’
FACT: A Deep Sky Object is defined as an astronomical object that is not part of our solar system.
Deep Sky Objects include:
- Globular Clusters of Stars,
- Open Clusters of Stars,
- Dark Nebula,
- Planetary Nebula,
- Diffuse Nebula,
- Supernova remnants,
- Galaxy Groups,
- Gravitational Lenses and Quasars. (But not single Stars!)
Within the Constellation Cassiopeia
The Constellation of Cassiopeia is formed by of a number of different components.
The different components housed by the Constellation Pegasus are mainly Stars, Deep sky objects and Messier objects (galaxies).
There are many different types of Stars in the star system categorized by size, lifespan and luminosity.
Generally, larger Stars have a shorter lifespan.
Stars are formed from clouds of interstellar gas and include:
Red Dwarf Stars
Most of the stars in the galaxy are Red Dwarf Stars. They are small in size measuring about 40-50% of the mass of The Sun. They are cool and their luminosity has only about 10% of the brightness of the Sun (our brightest Star), and they live for longer.
Brown Dwarf Stars
These are known as failed stars that form like other stars but don’t reach the mass, heat or density to begin the nuclear fusion process. They are only about 8% of the mass of the Sun and are red not brown, and not easy to spot in the night sky.
Red Giant Stars
These are giant luminous stars that have a low or medium mass. A Red Giant Star is formed when a star expands its volume by fusing all of its hydrogen into helium, and then burning the helium to produce carbon and oxygen to expand.
These are giant, bright stars that range from 10-100 times the size of the Sun and are 1000 times brighter. They are big and hot and therefore burn out quickly. The biggest are called Blue super giants or hyper giants. The biggest ever discovered was about 10 million times brighter than the Sun,
These are main-sequence stars like the Sun, but only 80% of its size, and are bright stars,
These are small burnt out husks of stars, about the same size as the Earth. White Dwarfs are dense and represent the final state of evolution for a star, like most stars in the galaxy.
These are the remains of a White Dwarf after it cools and darkens. This is likely to happen after about 10 billion years of life.
These are also main-sequence stars like the Sun, but twice the size, and are bright stars and hot.
Other types of stars include the Orange Giant, Neutron stars, Variable Stars and Binary Stars
What is a Bright Star?
The sky is home to various bright stars. The brightness of a star is measured by a value called its magnitude and they come in different sizes, composition, mass and color.
Their vast distance away from us is measured in light years from either the Earth or the Sun.
The lower the magnitude value the brighter the star appears in the night sky when viewed from Earth.
FACT: The Sun is considered to be the brightest star in the sky.
Cassiopeia has 15 formally named stars that have been officially approved by the International Astronomical Union (IAU):
As well as Stars, the Pegasus Constellation also has deep sky objects and galaxies (or even globular clusters or open clusters).
Deep Sky Objects
FACT: A Deep Sky Object is an astronomical object, that is not a solar system object like the Sun, Moon, Comet or a Planet. An individual Star is not considered to be a Deep Sky Object.
Deep Sky Objects are faint objects that can still be observed by the naked eye in the night sky from Earth.
They include Galaxies, Star Clusters and Nebulae.
What is a Nebula?
A Nebula is a massive cloud of gas and dust in Space.
Some Nebulae are formed when a star explodes and then dies, as is the case with a Supernova. Sometimes they can act as Star nurseries and are the areas where new Stars are forming.
The Nebulae are the spaces in between the stars referred to as interstellar space.
The heart and Soul of Cassiopeia
The Heart Nebula (IC 1805), with its red glowing gas and dust forming the shape of a heart, is an emission Nebula within the Cassiopeia Constellation. It is located approximately 7,500 light years from Earth. It is also referred to as the Running Dog Nebula.
The Soul Nebula (Westerhout 5), is also an emission Nebula located near the Heart Nebula in Cassiopeia
Images of the Nebulae have been captured using professional Space telescopes, such as the NASA Spitzer Space Telescope, operated by NASA, and the famous Hubble Space Telescope.
What is a Messier?
A Messier is a cluster of Stars
There are two Messier objects within Constellation Cassiopeia called Messier 103 (NGC 581) and Messier 52 (NGC 7654).
It was Charles Messier, a French astronomer, who is credited with cataloging each of the Messier Star clusters, around 1764.
He is famous for publishing an astronomical catalogue that lists 110 nebulae and star clusters, known as the New General Catalogue (used in its abbreviated form NGC and numbered).
These later became known as the Messier objects.
Messier 103 (M103), NGC 581 is an Open Cluster with a few thousand stars within the Constellation ofCassiopeia is one of the most distant open clusters found in the galaxy, estimated to be around 25 million years old.
This open cluster is some 8,000 – 9,500 thousand light years from Earth and is estimated to have around 172 stars in it
Messier 52 (M52), known as NGC 7654, is also an Open Cluster of stars located in the Constellation of Cassiopeia
FACT: A star cluster is a large group of Stars that can be Globular Clusters or Open Clusters:
A global cluster is a spherical collection of ‘Old Stars,’ numbering hundreds to millions, that are tightly bound by gravity and orbits a galactic core.
An open Cluster is a looser formation of ‘Young Stars’ that generally has less than a few hundred Stars.
NGC 457 is an open cluster in Cassiopeia, estimated to be 21 million years of age that lies around 7,900 light years from the Sun.
NGC 457 is also designated Caldwell 13, and referred to by the names: Owl Cluster, Dragonfly Cluster, Kachina Doll Cluster or the NGC 457 E.T. Cluster.
The Messier Marathon
The best time of year to view all 110 Messier objects at the same time, if the night sky conditions are positive, is between mid to late March and early April.
A supernova remnant is the structure that’s left after a star explodes in a supernova.
There are 3 types of supernova remnants: shell-like, composite and mixed-morphology (or thermal composite).
- Cassiopeia A (Cas A) is a shell-like supernova remnant within Cassiopeia. It is located approximately 11,000 light years from Earth.
It is the brightest extrasolar radio source in the sky at frequencies greater than 1 GHz.
- Cassiopeiae B (B Cas) is also referred to as SN 1572, (Tycho Supernova or Tycho Nova) and is a supernova of Type Ia.
NGC 278 (an isolated bright spiral galaxy) is found in the northern circumpolar Constellation of Cassiopeia. NGC 278 is located close to the southern constellation boundary with Andromeda.
Itlies approximately 9,000 light years from Earth and 39 mega light years from the Milky Way.
What is the Milky Way?
The Milky Way is a Spiral Galaxy, containing over 200 billion Stars, and forms part of the Constellation of Sagittarius.
It is the Galaxy that contains our solar system and it gets its name from the fact that it looks like a hazy swirl or river of milk across the sky, when viewed from earth.
It is made up of gas, dust and stars, with spiral arms wrapped around it, and a massive black hole in the center of the Galaxy.
Not all of the Stars in the Universe are contained within the Milky Way. Not even close. Rather, the Milky Way is one in what is estimated to be well over 100 Billion galaxies!
It is at its brightest if looking towards the galactic center in the direction of Sagittarius.
A section of the Milky Way runs through the constellation of Cassiopeia, containing open clusters, nebulae and young luminous galactic disc stars.
Background & Facts:
The Greeks were the first ancient culture to name the 88 Constellations in the sky.
It was the Greek Astronomer – Ptolemy, who first cataloged the Constellation of Cassiopeia, in the 2nd Century (2 AD.).
Ptolemy listed the various constellations in his Almagest (a book recording astronomical data).
In 1903, The German Astronomer – Johann Bayer, systematically assigned names to the 26 brightest stars in Cassiopeia and cataloged them in his Star atlas – ‘Uranometria’.
The Bayer designations are stellar designations where the stars within Constellations are initially identifiedby a name or a letter from the Greek Alphabet fromAlpha through Omega (in order of brightness).
1. The names of the Stars begin with a Greek letter starting with– Alpha
2. Followed by the genitive form of their parent constellation’s Latin name – ‘Cassiopeia’ with ‘e’, makes the name ‘Cassiopeiae’
3. Giving the name Alpha Cassiopeiae
The main stars of Cassiopeia are named by their apparent magnitude (luminosity) from the brightest to faintest star in decreasing order:
- Alpha Cassiopeiae – Schedar (the brightest Star in Cassiopeia, is a second magnitude star. It is usually declared to be the brightest Star, an orange giant star in Cassiopeia, located around 230 light years from Earth, eventhough the Beta Cassiopeiae Star has a similar level of visual brightness.
- Beta Cassiopeiae – Caph, (the second brightest Star, or possibly joint brightest star, in Cassiopeia, and is a Giant Star). It is a Delta Scuti variable Star, with a magnitude of +1.16
- Delta Cassiopeiae – is an Eclipsing Binary Star System in the northern circumpolar constellation of Cassiopeia and approximately 99.4 light years from Earth
- Rho Cassiopeiae – is a yellow hyper-giant Star, about 3,400 light years from Earth, and 300,000 times brighter than the Sun, but can still be seen by the naked eye
- Gamma Cassiopeiae – y Cas, (nicknamed Navi),is a spectroscopic binary Star. This Star has an apparent variable magnitude of 1.6 – 3.0, so it is sometimes seen as being brighter than its otherbright star neighbors in Cassiopeia– Schedar, Caph and Segin
- Epsilon Cassiopeiae – Segin, (one of the brightest Stars with an apparent visual magnitude of 3.4, and located around 390-430 light years from the Sun)
- Eta Cassiopeiae– another Binary Star System in the northern circumpolar constellation of Cassiopeia, 19.42 light years from the Sun. It has 2 components referred to as Eta Cassiopeiae a andEta Cassiopeiae b
- 50Cassiopeiae – NGC 771, is a white star that’s visible by naked eye with a magnitude of +3.95
- HR 219134 – (a main sequence star, that’s less luminous and smaller than the Sun)
- Mu Cassiopeiae – (a binary star system, that shares the Marfak with Theta Cassiopeia, meaning the elbow
- HD 209458 – (an 8th magnitude star, 159 light years from Earth and not visible by naked eye)
How do the Bright Stars of Cassiopeia form a letter W shape?
The Bright Stars
If you look up and into the night sky you can imagine the recognizable outline of the Constellation of Cassiopeia, which is a large W shape.
This main constellation is made up of 5 bright Stars (from the left point of the W shape to right): – Segin, Ruchbah, Gamma, Schedar and Caph.
Although around 93 stars can be seen by the naked eye in the night sky on a clear night (many cannot be seen without binoculars of special telescopes)
Stars with Planets
Cassiopeia has 3 Bright Stars and 20 Star systems with exoplanets orbiting around them in the solar system but they are unlikely to be able to support life forms.
The furthest exoplanet discovered was actually in the Andromeda Galaxy, not in the Milky Way.
Not all the stars within the Cassiopeia Constellation are visible to the naked eye but with telescopes and modern imagery techniques is it possible to glimpse all of the stars.
FACT: An exoplanet (also referred to as an extrasolar Planet) is a planet that orbits a Star that is not located within our Solar System (exoplanets do not orbit our Sun)
Nothing stands still in the sky.
Planets are continually being discovered and lists updated.
The Constellations change their positions throughout the year as the Earth rotates around the Sun.
This means our position in space is forever changing and as a result our view of what’s in space changes too, and will continue to do so.
What is the purpose of Cassiopeia? –
In ancient times the dots, bright lights and perceived objects in the sky were of great interest and the makings of folklore to a great range of people from seamen to farmers.
From children to the elderly, we have had an ongoing fascination, with our solar system and star system. Perhaps it’s because the enormity and variety within it makes us realize just how large and exciting the universe is.
FACT: The Star System or Stellar System is a small number of stars that orbit around each other and are bound together by gravity.
When it becomes a large group of stars, again bound together in the same way, by gravity, it is known as a Galaxy or Star Cluster.
Whether they contain small groups of stars or larger groups of start the both come under the classification of ‘Star System’.
The Cassiopeia celestial pole
The celestial pole defines the poles of the celestial equatorial coordinate system.
- The declinations for the north celestial pole is +90 degrees
- The declinations for the south celestial pole is -90 degrees
The celestial poles are not permanently in a fixed position against the background of the stars as everything moves in Space.
Navigational tools in the sky
The many Constellations in the night sky were a useful navigation tool and guide as well as the subject of legends and myths, about heroes like Zeus, the god of the sky and his brother Poseidon, the god of the seas and other powerful gods.
42 of the Constellations have been named after animals with a story behind each name.
The neighbors of Constellation Cassiopeia
The Constellation of Cassiopeia is neighbored by several constellations in the Northern Sky: The shape of the W forms the outline of the Constellation of Cassiopeia in the sky.
The other well-known neighbors include Perseus, and Cepheus.
Historical significance: the legends, and myths surrounding Constellation of Cassiopeia
When it comes to the many recognized constellations in the sky, Cassiopeia is one of the oldest recognized Constellations.
When Ptolemy, the Greek astronomer, catalogued Cassiopeia as far back as the 2nd century, it became a topic of great interest in Greek mythology and in other ancient civilizations.
However the origins of the earliest Constellations probably date back to prehistory. Many ancient civilizations have related the Constellations in the sky to suit their beliefs and creations itself. They have been the subject of folklore and experiences for a very long time.
There are many Greek myths and legends surrounding the origin, origin and names of the constellations, involving gods like Zeus, and his son the hero Perseus, and even mythical creatures like Gorgons andCetus the Sea Monster.
The Constellation of Cassiopeia was previously known as Cassiopeia’s Chair by astronomers and sky-gazers and later as Cassiopeia the Queen.
The Myth of Cassiopeia (the queen of Ethiopia)
The name ‘Cassiopeia ’ is of Greek origin and means ‘Clever’.
Cassiopeia, the wife of King Cepheus, of Ethiopia, was a boastful queen known for her vanity and eventually changed into a constellation. Together they had a daughter Andromeda. Cassiopeia was very vain, and boasted that she was more beautiful than all of the 50 Nereids (the Sea Nymphs). The Sea Nymphs were so angry that they went to Poseidon, the god of the sea, who was married to one of the Sea Nymphs (Amphitrite) and asked him to punish Cassiopeia.
He obliged and sent the Sea Monster Cetus to ravage the kingdom. To appease the Sea Monster, Cassiopeia tied her daughter Andromeda to a rock for him to eat. The hero Perseus, on his winged horse Pegasus rescued Andromeda just in time, from being devoured by Cetus. They married and lived happily ever after. The gods were so happy at the outcome that they placed them in the heaven as stars.
However, to show their displeasure with Cassiopeia she was tied to a chair and put in the heavens where she revolves around the celestial pole, sometimes in an upside down position.
Ancient associations with the constellations
The Greeks, the Romans and the Sumerians all had an interest in the constellations in the sky.
The Sumerians were the first literate civilization of the Ancient Mesopotamia (an area occupying parts of Turkey and the Syria of today, Iraq, Iran)
The Sumerian civilization was not unified like the ancient Greek or Roman civilizations it was bonded by a common attitude.
Their belief systems featured many deities. They regarded their gods as being responsible for everything and as such held them in great respect. Many stories arose as a result.
For thousands of years, various cultures around the world have identified and named the constellation we know and see in the night sky as Cassiopeia.
The Mesopotamian civilization (the first known civilization) identified constellations like Cassiopeia
FACT: The ancient lands of the Mesopotamians now stretches across Turkey, Syria, Iraq and Kuwait
Cassiopeia and the other constellations in the sky were not only the subject of legends but they had a practical use too.
The ancient Mesopotamians used the orientation of the constellations to set the seasons for sowing crops and harvesting.
The Babylonians also recorded details of various bright stars within the constellations in their Babylonian star catalogues before 100BCE.
What is the difference between a constellation and an asterism?
An asterism is a group of stars that appear to form a pattern in the night sky but with no officially determined boundaries.
It can make up part of a constellation or cross the boundaries of an official constellation or even a defunct constellation.
An asterism is a more vague assembly of stars than a recognized constellation.
The meteor showers
The annual meteor showers associated with the Constellation of Cassiopeia are known as the ‘Perseids’.
The Perseids are one of the brightest meteor showers and are associated with its parent body the comet ‘Swift-Tuttle’. The point they appear to come from lies within the constellation of Pegasus.
The name comes from the Greek word Perseidai meaning the ‘sons of Perseus’
The Perseids meteor shower occurs between July 23 and August 20 each year. Its peak around August 9-13 every year and is visible in the Northern Hemisphere.
The meteor shower is associated with the constellation of Perseus because the point at which they appear is located in that direction.
In the Catholic religion the Perseids are referred to as the ‘tears of Saint Lawrence’.
This Saint was burned alive and the story according the Mediterranean folklore is that he returns to earth every year on August 10, as a shooting star (the date of the Saint’s martyrdom).
When the embers from the meteor shower cool they appear under plants as earth.
Fun Facts about Constellation Cassiopeia – Did you know that?
- The brightest star in Cassiopeia is Schedar (a Cas)
- The Constellation of Cassiopeia has several nicknames: The Lady of the Chair, Cassiopeia’s Chair, Lazy M or Celestial M
- There are over 4000 known exoplanets, with another 5000 awaiting classification
- The scale of a Constellation is measured in square degrees
- Charles Messier the French Astronomer who cataloged the Messier objects has a crater on the Moon named after him.
- Constellations like Cassiopeia are not part of our Solar System; they are groups of stars that appear to form shapes that are visible by naked eye from Earth.
- The largest Constellation is called Hydra and the smallest Constellation is called Crux.
- The Sun does not belong to any constellation.
- A Constellation does not actually exist as a fixed object, it is a group of bright stars that happen to be in a random place and are light years apart and ever moving. We see the pattern of their presence.
- The Nasa Chandra X-ray Observatory has captured many images of cosmic phenomena including the supernova remnant Cassopeia A (Cas A).
- The center of a Galaxy does not contain a Giant Star it contains a massive Black Hole.
- Red Dwarf is not a Dwarf Planet it is a Star. Most common Stars are Red Dwarf (cool Stars)
- Spiral Galaxies make up about two third of all the Galaxies in the Universe
Commonly Asked Questions
Q. What is the celestial sphere?
A. In astronomy and navigation terms, the celestial sphere is imaginary.
This virtual sphere has a large radius that is concentric with Earth.
We can imagine all objects in the night sky as being projected upon the inside of this celestial sphere, as if it has images placed inside a dome.
Q. What prevents us seeing the Stars and Constellations in the night sky?
A. Light pollution, fog, city lights and artificial lights all limit our visibility of the objects in the sky at night.
The best views come from outside of cities where light pollution is less. Camping in the countryside is one of the best ways to get a better view of what’s up there in Space.
Q. Will the Constellations change over time?
A. The Constellations are continually on the move.
The images we form in our imagination to make objects, shapes and patterns out of the constellations have already shifted over time.
As we view the night skies from Earth they are likely to continue to shift and possibly in time the images may look very different.