First of all, what is a constellation?
Before we dive into the Pegasus Constellation, let’s first take a look at what exactly a constellation is.
A constellation is an area on the celestial sphere (an imaginary sphere) where a group of visible stars are located.
These stars typically form a pattern or outline, which we perceive to represent an inanimate object, (like a question mark), an animal (like the Swan or Bear,) a mythical person (like Zeus or Medusa from Greek mythology) or even a type of creature (like Pegasus, a celestial winged-horse)
It is also an astronomy term used to describe a variety of groups of stars that have been given a specific name such as –
Constellations are constantly moving and move in the direction from East to West.
The Pegasus Constellation – Facts in brief:
What is it? –
The Pegasus Constellation is one of the oldest known constellations, and ranks as the 7th largest Constellation as one of the original 48 Constellations listed by Greek Astronomer Ptolemy.
It is officially one of the ICU listed 88 modern constellations as seen in the night sky from Earth.
Pegasus (its Latin name) is quite easy to recognize, as it clearly resembles the outline of a mythical creature that is a horse with enormous wings. It is symbolized as a white winged-horse.
The Pegasus Constellation is part of the Perseus family of Constellations.
Fellow Perseus family members include:
Where is it located? –
The Constellation of Pegasus is positioned north of the ecliptic plane in the Northern Hemisphere, between the constellations of Cygnus and Aquarius. It is sometimes referred to as being located in the NQ4 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 Pegasus.
The Stars of Pegasus can be observed from Earth in the Northern Hemisphere in the month of October, at 21.00 hours local time.
The right ascension for Pegasus is 22 hours, 12.6 minutes to 00.00 hours, 14.6 minutes.
The Declination of Pegasus is +2.33 to +36.61 degrees
It’s visible in the Northern Hemisphere at latitudes between +90 degrees and – 60 degrees and covers an area of 1121 square degrees in the sky.
The Pegasus Constellation is bordered by several other Constellations
- To the top – Cassiopeia, Andromeda, Lacerta, Cygnus and Vulpecula
- At the sides – Algenib and Delphinus
- To the bottom – Pisces, Aquarius and Equuleus
How can you identify Pegasus?
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.
Pegasus is represented as a winged horse in the night sky.
Pegasus is a Constellation that can be identified by locating its brightest stars, which form an asterism known as the Square of Pegasus.
It can be viewed from Earth by the naked eye.
The Star System of Pegasus
The brightest star in Pegasus is called Epsilon Pegasi (Enif).
It is an orange supergiant that represents the muzzle of the winged horse image.
The Constellation of Pegasus is easiest to identify in the Northern sky by identifying the asterism of stars known as the Square of Pegasus.
The four bright stars that form the ‘Square of Pegasus’ shape are:
- Alpha Pegasi (Markab)
- Beta Pegasi (Scheat)
- Gamma Pegasi (Algenib)
- Alpha Andromedae (Alpheratz or previously Delta Pegasi, is the brightest star in the Constellation of Andromeda)
It’s located 204 light years from The Sun, and 140 years from Earth with a magnitude of around +3.4. (that ranges from +0.7 – +3.5)
Pegasus is one of the largest constellations.
It is the combined light of the various bright stars in the star system that produces enough light to give Epsilon Pegasi (Enif) the brightest star status in the Constellation of Pegasus.
Enif is rich in Barium and Strontium and it is so big it could eventually die in a supernova explosion.
The name of the main Star ‘Enif’ is from the Arabic word ‘al-anf’ and means the ‘nose’, and represents the nose in the outline of the horse forming the image of Pegasus.
This name represents the position of the brightest star in the recognizable image of the mythical winged horse.
The supergiant Enif Star is almost 4000 times brighter and over 12 thousand times brighter when measured by bolometric luminosity. It is cooler and younger, than the Sun and visible by naked eye from Earth.
Enif in Pegasus, is believed to have the same interstellar make up as the neighboring supergiant, bright stars within the Constellation of Aquarius and is located approximately 690 light years from our Solar system.
Spotting Pegasus in the night sky
The easiest way to spot the Constellation of Pegasus would be to locate the asterism collection of stars known as the great square of Pegasus. It is often described as a box with legs sticking out of it.
Find the 4 main stars
- Algenib y
As well as the top star Scheat and the left point star of the square shape, Alpheratz, it is the stars Algenib y and Markab which represent the bottom two corner points of the square.
Imagine a line running from the star Markab downward through the Homam star, (along the right hand side of the great square of Pegasus) to a point at the end of a ‘V’ shape. Then continue that line upward again to the Bright Star Enif (Epsilon Pegasi) – that forms the main line of Pegasus (Peg).
Draw an imaginary outline
The next step is to try to imagine the surrounding shape of the winged horse, by joining the illuminated dots (the other bright Stars).
The points of the Stars represent the main parts of the winged horse
- Enif – represents the nose of the horse
- Bilham – the side of the head underneath the ear
- Homan – the neck
- Markab and Algenib – represent the start and end of the wing
- Sadalbari, Kerb, Scheat and Matar represent the top of the legs to the knee.
- Alpha Andromeda – represents the belly
This simple technique can be used to spot other Constellation patterns too like the Question Mark or other mythical creatures from Greek mythology.
Location of Pegasus
The Constellation Pegasus is surrounded by various recognizable Constellations: Aquarius, Pisces, Andromeda, Lacerta, Cygnus, Vulpecula, Delphinus and Equuleus.
Pegasus can be spotted in the Northern Hemisphere, also referred to as the Northern sky.
The Square of Pegasus 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 Pegasus
The best months to spot the Constellation of Pegasus, the celestial Winged Horse in the Northern Hemisphere is from LateSeptember to Early October.
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?
The Constellation of Pegasus ranks as the 7th biggest 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 1121 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 the line patterns and shapes they are referred to by.
There are many different Stars and Deep Sky Objects within the Constellation Pegasus.
The Constellation of Pegasus contains nine stars with confirmed planets and one Messier Object (Messier 15,M15, also referred to as NGC 7078), and one associated meteor shower.
Other Deep Sky Objects within Pegasus include the Einstein Cross (a gravitationally lensed quasar), Stephan’s Quintet of galaxies and NGC 7742 (an unbarred spiral galaxy).
FACT: a Quasar is a quasi-stellar object (QSO), a highly luminous astronomical object found at the center of some galaxies. This active galactic nucleus (AGN) has a massive black hole (billions of time larger in mass than the Sun), which is surrounded by a gaseous accretion disk.
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 Pegasus, 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, assigned systematic names to the brighter stars 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 (usually in order of brightness).
This is then followed by the genitive form of their parent constellation’s Latin name – ‘Pegas’ with ‘i’, to give ‘Pegasi’
The named stars of Pegasus, range in luminosity from the brightest Star (Enif, also known as Epsilon Pegasi), in decreasing order of luminosity:
- Epsilon Pegasi – Enif (the brightest Star in Pegasus, an orange Super Giant. It is located around 38-70 light years from The Sun, and hotter than the Sun)
- Beta Pegasi – Scheat (the second brightest Star in Pegasus, and is actually a Red Giant)
- Alpha Pegasi – Markab the third brightest Star in Pegasus is an A-type sub giant star
- Gamma Pegasi – Algenib (the fourth brightest Star in Pegasus is another sub giant star)
- Eta Pegasi – Matar (the fifth brightest Star in Pegasus is a binary Star)
- Zeta Pegasi – Homam, (a single Star that is visible to the naked eye with a magnitude of +3.4, 204 light years from the Sun)
- 51 Pegasi – Helvetios (is a Sun-like Star, first discovered to have an orbiting exoplanet and around 50 light years from Earth)
- HR 8799 – (a main sequence star, 129 light years from earth and estimated to be over 30 million years old and brighter and bigger than the Sun)
- IK Pegasi – (a binary star system, 154 light years from Earth)
- HD 209458 – (an 8th magnitude star, 159 light years from Earth and not visible by naked eye)
FACT: An exoplanet is a planet that is not located within our Solar System
The importance of the Constellation Pegasus dates way back to the times of the Babylonians who identified a constellation IKU (field) with 4 bright stars.
3 of those Bright Stars were acknowledged by the ancient Greek civilizations as the Constellation Hippos (Hippocrene), commonly referred to as Pegasus.
Both these ancient civilizations referred to Pegasus (Hippocrene) as the celestial winged-horse with magical powers.
How do the Bright Stars of Pegasus form the shape of a horse with wings?
The Bright Stars
If you look up and into the night sky you can imagine the recognizable outline of the Constellation of Pegasus, which is an upside down, celestial avatar of a horse with wings where the different parts of its body are represented by other stars.
Stars with Planets
Pegasus has 5 Bright Stars and 12 Star systems with exoplanets orbiting around them in the solar system but they are unlikely to be able to support life forms. 51 Pegasus was the first discovered with an exoplanet.
Not all the stars within the Pegasus Constellation are visible to the naked eye but with telescopes and modern imagery techniques is it possible to glimpse all of the stars.
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.
Why and what is the purpose of Pegasus? –
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 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.
Background & Facts:
The neighbors of Constellation Pegasus
The Constellation of Pegasus is neighbored by several constellations in the Northern Sky: The Great Square of Pegasus is the guide point for finding the Constellation of Pegasus in the sky.
The other well-known neighbors include Aquarius, and Pisces.
Within Constellation Pegasus
The Constellation of Pegasus 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.
Pegasus has 15 formally named stars that have been officially approved by the International Astronomical Union (IAU):
- Algenib, Alkarab, Anadolu, Biham, Enif, Helvetios, Homam, Markab, Matar, Morava, Sadalbari, Salm, Scheat, Solaris and Tangra
As well as Stars, the Pegasus Constellation also has deep sky objects and galaxies (or even globular 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.
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.
Messier – a cluster of Stars
There is only one Messier object within Constellation Pegasus and it is called Messier 15, also known as the Great Pegasus Cluster (a global cluster in the Northern Constellation Pegasus).
It was Charles Messier, a French astronomer, whois credited with cataloging the Messier Star clusters, around 1764.
He is famous for publishing an astronomical catalogue that lists 110 nebulae and star clusters.
These later became known as the Messier objects.
Messier 15 (M15) located in the Constellation of Pegasus is one of the oldest known globular clusters found in the galaxy, estimated to be around 12 billion years old.
This cluster is some 33,600 light years from Earth.
It has a magnitude of 6.2 and the designation of NGC 7078 within the New General Catalogue (used in its abbreviated form NGC).
FACT: A star cluster is a large group of Stars that can be Globular or open
- Globular 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.
- Open Clusters:
An open Cluster is a looser formation of ‘Young Stars’ that generally has less than a few hundred Stars.
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.
NGC 7331 (a spiral galaxy) is also found in the Northern Constellation of Pegasus. NGC 7331 is located around 49 million light yearsfrom Earth and is approximately 100,000 light-years across.
The NGC 7331 spiral galaxy is a group of Galaxies, also referred to as ‘The Deer Lick Group’, and NGC 7331 is the brightest member of the group.
There is a supermassive black hole at the center that is roughly the same size as the black hole at the center of 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. The Milky Way itself is not a Constellation of Stars. 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.
It is at its brightest if looking towards the galactic center in the direction of Sagittarius.
The Stars that make up the Milky Way are many light years away and cannot be individually identified by the naked eye.
Historical significance: the legends, and myths surrounding Constellation of Pegasus
When it comes to the many recognized constellations in the sky, Pegasus is one of the oldest known Constellations.
When Ptolemy, the Greek astronomer, catalogued Pegasus as far back as the 2nd century, it became a topic of great interest in Greek mythology and in other ancient civilizations.
There are many Greek myths and legends surrounding the origin and names of the constellations, involving gods like Zeus and even mythical creatures like ‘Pegasus the wild winged-horse’.
The name ‘Pegasus ’ is of Latin origin and means ‘born near the water’ or a winged horse, or even abird with the head of a horse.
Pegasus is believed to be the offspring of Poseidon, Olympian god of the Seas and water (Father), with the Gorgon Medusa (Mother).
Perseus cut the head off the Gorgon Medusa and Pegasus was created from her blood. (It is believed that Athena was born in a similar manner from Zeus).
The taming of Pegasus
It is believed that Pegasus was a wild horse with wings that roamed freely.
‘Bellerophon’, was a Greek monster slaying hero, (like Perseus). He tamed Pegasus with help from the goddess ‘Athena’ when she gave him a magical golden bridle.
Bellerophon used the golden bridle to capture Pegasus as he drank at the Pierene fountain. He then tamed Pegasus and rode him in battle to defeat the Chimaera.
FACT: In Greek Mythology, the Chimaera was a monstrous fire-breathing creature from Lucia that was made up of the parts of several animals – the body of a lion, head of a goat sticking out of its back and a tail with a snake’s head at the tip.
Bellerophon eventually fell off Pegasus on his quest to reach Mount Olympus.
Zeus is the god of the sky and thunder. He rules as the king of the gods of Mount Olympus.
Pegasus served Zeus for many years and carried his thunderbolts.
To reward him for his loyalty, Zeus finally transformed Pegasus into the Constellation referred to today as Pegasus in the Northern Sky.
The Hippocrene Spring Myth
Hippocrene means ‘Horse’s Fountain’.
Pegasus was thought to use his hooves to dig out of the spring of Hippocrene, located on Mount Helicon.
The water from the spring was said to bless all those who drank the water with the ability to write poetry.
There are several mentions of this magical spring in poems:
- The Poet, John Keats mentions Hippocrene in the well-known poem ‘Ode to a Nightingale’.
- Poet, Petrarch mentions the fountain of Mount Helicon in his poem ‘Africa’.
- The Poet, Henry Wadsworth Longfellow mentions the fountain in his poem ‘Goblet of Life’.
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 Pegasus.
The Mesopotamian civilization (the first known civilization) identified constellations like Pegasus.
FACT: The ancient lands of the Mesopotamians now stretches across Turkey, Syria, Iraq and Kuwait
Pegasus 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 ‘Big Dipper”?
When we take an interest in the different objects in the night sky one of the first patterns we learn to recognize is the ‘Big Dipper’.
The Big Dipper is not a constellation it is an asterism.
In fact, The Big Dipper is the best-known asterism and one of the most easily recognized patterns in the northern sky at night. It is within the Constellation Ursa Major (the Great Bear).
The Big Dipper is known by different names across the world but it is the same arrangement of stars forming the pattern. It is also known as:
- The Plough, the Saucepan, and the Great Wagon
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 Pegasus 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 17 and August 24 each year. Its peak around August 9-13 every year and is visible in the Northern Hemisphere.
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 in the earth and are then described as ‘the coal of Saint Lawrence”.
Fun Facts about Constellation Pegasus – Did you know that?
- The brightest star in Pegasus, Enif, is known as a young star and is much younger than The Sun, even though it is 20 million years old
- 51 Pegasi b was the first planet discovered to be orbiting around a Star, like our Sun.
- 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 Pegasus are not part of our Solar System; they are groups of stars that appear to form shapes that are visible with the naked eye from Earth.
- 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.
- A ring of molecular gas and new Stars extends out of the core of NGC 7331. Within this collection of gas and dust there is enough raw material to create 4 billion Suns.
- 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)
- The NGC 7331 galaxy has two type II supernova identified within it – SN 1958D and SN2013bu
- The Asterism of Pegasus has between 9 and 17 main Stars depending how you classify it.
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.
- spring of Hippocrene, located on Mount Helicon