First of all, what is a constellation?
All constellations, including the Libra constellation, are basically a group of Stars. A constellation is an area on the celestial sphere (an imaginary sphere) where a group of visible stars are located.
The Constellations of the Zodiac lie along the plane of the ecliptic (the apparent path of the Sun, defined as the circular path of the Sun across the sky).
These stars typically form a pattern or outline, which we perceive to represent an inanimate object, (like the weighing scales or a question mark), an animal (like the fishes), a mythical person (like Andromeda or Astraea, from mythology) or even a type of creature (like Pegasus)
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 Constellation Libra – Facts in brief:
What is it? –
Libra was once considered to be a part of the Constellation of Scorpius and some of the stars have a meaning relating to the claws of a Scorpion.
The Libra Constellation is an ancient Constellation and one of the first 48 Constellations listed by the Greek/Roman astronomer Ptolemy in his 2nd century Almagest. It is one of the 12 constellations of the zodiac.
Libra ranks as the 29th largest constellation within the 88 modern constellations as seen in the night sky, and the 7th largest constellation of the Constellations of the Zodiac.
In Latin, the name Libra means ‘Balance’ as in ‘ the Scales’.
Libra, sometimes abbreviated to ‘Lib´, is quite easy to recognize, in the sky as it resembles a set of weighing scales that rest on a beam with weighing pans on either side: if you join the dots and use your imagination.
Libra is a faint constellation that does not contain any first magnitude Bright Stars.
FACT: A first Magnitude Star has an apparent magnitude of 2.55 or brighter. (In a typical dark sky Stars with an apparent magnitude up to +6.0, should be possible to view by the naked eye)
Locating a Constellation
It can seem daunting at times trying to locate your favorite Constellation in the great night sky.
However, if you can imagine an invisible coordinate grid draped over the dark sky it becomes easier.
Using the longitude and latitude coordinates of this grid it is possible to locate Constellations, the Asterisms of Main Stars and other Deep Sky Objects.
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 Libra.
The Stars of Libra can be more easily observed from the Southern Hemisphere, and also it can be viewed from the Northern Hemisphere.
In the Southern Hemisphere
The Constellation of Libra is found at 15 hours, 30 minutes right ascension and a 15-degree South declination, and covers an area of 538 square degrees in the sky.
In the Northern Hemisphere
It is also visible in the Northern Hemisphere.
Where is it located? –
- Libra is positioned in the 3rd quadrant of the Southern Hemisphere, close to the celestial equator.
- It is sometimes referred to being located in the SQ3 Quadrant.
- It is located between two other Zodiac Constellations –
Constellation Scorpius and Constellation Virgo, and is visible from most points on Earth.
Libra has a number of neighboring Constellations, which can help locate this Constellation.
How can you identify Libra in the night sky?
The simplest method for spotting any particular Zodiac Constellation from Earth is to first of all locate the brightest stars in that Constellation, and then look at the neighboring illuminations, to see if you can identify a recognizable pattern.
Libra is usually represented as ‘the Scales’, or the ‘Balance’.
The Libra Constellation is often depicted as a set of balancing scales with two weighing pans, held by the goddess Dike (also known as Astraea) the Greek goddess of justice, or Lady Justice.
Dike (Astraea), the Greek, Roman goddess, is usually associated with the Constellation Virgo.
The Constellation Virgo is represented as an angel, or virgin, with large wings, holding a long ear of wheat in her left hand.
The brightest Star Spica represents the ear of wheat or a palm leaf.
Libra is a zodiac Constellation located within the Milky Way and although it is faint in luminosity it’s still visible by naked eye from most points around the world in the Northern sky and Southern sky.
Tips for Spotting Libra in the night sky
The easiest way to find Libra is to
1. Firstly locate the famous ‘Big Dipper’ (in the Constellation Ursa Major)
2. Look down to find the 4th brightest Star in the sky, Arcturus in Constellation Bootes
3. Look down again from Bootes to find Virgo
4. Virgo is next to Libra
How do you know it is Libra?
The four brightest Stars in Libra form the shape of a quadrangle
The easiest way to spot the Scales of Libra, would be to locate its two brightest Stars alpha Librae and beta Librae in the Southern sky.
The next step is to draw a line between these two bright Stars, and try to imagine them forming the shape of the balancing beam, with one Star at each end.
The two other main Stars in Libra, Gamma Librae and Sigma Librae (known as Brachium) represent the weighing pans balanced on the scales.
This simple technique, of joining the dots, can be used to spot the other Constellation patterns too like ‘the Twins’ (in Gemini).
The Constellation Libra is located between the Constellation Virgo to the West and the Constellation Scorpius to the East.
So, if you find the quadrangle of bright Stars in the sky that is how to create the image of Libra
The Constellation of Libra is most prominent in the Southern Celestial Hemisphere, if looking South during the month of June around 21.00.
How is it formed and named?
The Constellation of Libra ranks as the 29th largest Constellation overall in the sky and the 7th biggest zodiacal constellation in the Celestial Sky, filling an area of 538 square degrees.
It has a simple and easy to identify shape like a set of weighing scales formed by the positions of its 4 main Stars.
The Constellation of Libra is the only Constellation of the Zodiac not named after an animal or a character from either Greek or Roman Mythology.
Its Latin name ‘Libra’ is abbreviated to ‘Lib’ by the International Astronomical Union (IAU), and to ‘Libr’according to a naming convention adopted by NASA.
The Star System of Libra
The Constellation of Libra is one of the fainter constellations as it has only two stars with an apparent magnitude brighter than +3.0, namely:
- Zubeneschamali, an Arabic name meaning ‘the Northern Claw’ (once referring to the Northern Claw of Scorpius)
- Zubenelgenubi an Arabic name meaning ‘the Southern Claw’ (once referring to the Southern Claw of Scorpius)
The stars of the Constellations are listed by letters of the Greek alphabet, ranging in luminosity from the brightest Star, and usually start with Alpha, and then the rest of the stars list in decreasing order of luminosity through the Greek alphabet.
However in the Constellation of Libra – the brightest Star is designated the beta Star title and the second brightest Star is the alpha star.
The Brightest Star
The brightest star in Libra is called Zubeneschamali.
This Star was originally regarded as part of the Constellation of Scorpius, not Libra.
It is now considered as a part of Libra but it has not been allocated the alpha star name in the Constellation. Zubeneschamali, the Brightest Star in Libra is known as ‘Beta Librae, b Lib’.
The second brightest Star, Zubenelgenubi, has been designated as the ‘alpha Librae, a Lib’ Star.
It is a suspected variable Star that is located approximate 185 light years from our Sun with an apparent magnitude of 2.61.
The main Stars in Constellation Libra
There are 83 different Stars within Libra with an apparent visual magnitude of +6.5 or brighter (visible to the naked eye in a dark sky)
As well as Zubeneschamali and Zubenelgenubi the other main Stars forming the outline of Libra include:
- Sigma Librae, or Brachium (previously designated Gamma Scorpii)
- Upsilon Librae
- Tau Librae
- Gamma Librae, or Zubenelhakrabi
- Theta Librae
Gliese 581 is one of the oldest and least active of the Red Dwarf Stars, and forms the centerpiece of the Gliese 581 planetary system.
This planetary system contains at least 3 planets.
It is around 20 light years distant from Earth and known in exoplanetary investigations looking for life on other planets that are located close to Earth and our Solar System.
Gliese 591 is estimated to be about one third of the size of the Sun and the 89th closest known Star to the Sun.
It is located approximately 2 degrees North of the brightest Star Beta Librae.
The Methuselah Star, also known as HD 140283, is one of the oldest known Stars located in the Milky Way and possibly older than the Universe itself.
It is a luminous blue-white Giant Star calculated by NASA to be around 14.5 billion years of age.
Who, or what represents Libra? –
The Constellation of Libra is represented by ‘ various images of ‘Balance’
The reason is that it looks very similar to the outline of a set of weighing scales.
The main Stars
If you look up and into the night sky you can imagine the recognizable outline of the Constellation of Libra illuminated by its 8 main Stars.
Stars with Planets
Libra has 4 Stars with known Planets, approved by the International Astronomical Union (IAU) orbiting around them in the solar system but they are unlikely to be able to support life forms.
The Constellation Libra has 4 named stars in its asterism that are approved by the IAU:
- Brachium, Zubenelgenubi, Zubenelhakrabi and Zubeneschamali
It also has a total of 56 stars that are designated by Bayer Flamsteed.
Not all the stars within the Libra Constellation are visible to the naked eye but with telescopes and modern imagery techniques is it possible to glimpse all of the stars.
When was it first discovered? –
Libra is one of the oldest known Constellations and was acknowledged as far back as the Babylonians, and the Sumerians.
The ancient Greeks
The ancient Greeks were the first ancient culture to name the 88 Constellations in the sky.
This area of the sky occupied by the Constellation of Libra was known as ‘Chelae’ or the ‘Claws’ as the ancient Greeks considered it part of the Constellation of Scorpio.
Chelae represented the claws of the Scorpion shape in the night sky.
The Romans connected this area of the sky with the scales in the 1st Century (1 A.D). They believed that the Moon was present in Libra when Rome was built and they considered this to be lucky.
They associated it with balance in the seasons and the period of the year when the amount of daytime and night time were equal: The Autumnal Equinox
The word ‘equinox ‘is from the Latin word ‘aequus’ meaning equal, and the word ‘nox’ means night.
The Autumnal Equinox (Autumn equinox) occurs in September, around the 22nd or the 23rd of that month.
An Equinox occurs twice in each year, known as the Spring Equinox and the Autumn Equinox and the Sun illuminates the Northern Hemisphere and the Southern Hemisphere equally.
It is like a balance in heaven is happening.
FACT: When the Sun is directly above the Earth’s equator the night and day is equal in length. These 2 points in the year are where the ecliptic intersects with the celestial equator.
The ecliptic is the imaginary line tracing the route that The Sun, the Moon, and the Planets take across the sky each year.
At the time of equinox the Northern Hemisphere will begin autumn as the Southern Hemisphere begins spring, and visa versa.
It was the Greek Astronomer – Ptolemy, who first cataloged the Constellation of Libra in the 2nd Century (2 AD.). Ptolemy listed the various constellations in his Almagest (a book recording astronomical data).
When referring to a Star within a Constellation it is given the genitive form of the Constellation name. (‘Libr’, with ‘ae’, giving Librae’).
FACT: In Latin, the genitive is the case of description.
The named Stars in Libra
Within the ConstellationLibra, the Stars would be referred to by: the name or the letter from the Greek Alphabet, in order of brightness followed by ‘ Librae’, (or their proper name) such as:
- Beta Librae, b Lib (Zubeneschamali)– is the brightest Star in the Constellation, and a suspected variable star, located around 185 light years from the Sun, with an apparent visual magnitude of 2.61
- Alpha Librae, a Lib (Zubenelgenubi)– is the second brightest Star in the Constellation, and a spectroscopic binary star, suspected variable star, located around 77 light years from the Sun, with an apparent visual magnitude around 2.75
- Sigma Librae, (Brachium)– is the third brightest Star in the Constellation, and a binary star, located around 288 light years from the Sun, with an apparent visual magnitude of 3.29
- Upsilon Librae, u Lib – is the fourth brightest Star in the Constellation, and a double star, located around 224 light years distant, with an apparent visual magnitude of 3.63
- Tau Librae, T Lib – is a binary star, located around 367 light years from Earth, with an apparent visual magnitude of 3.68
- Gamma Librae, y Lib (Zubenelhakrabi)– is a suspected binary star system, with 2 planets, located around 163 light years from the Sun, with an apparent visual magnitude of 3.91
- Theta Librae, b Lib (Zubeneschamali)– is a single orange-hued Star, located around 168 light years from Earth, with an apparent visual magnitude of 4.14
- Alpha Piscium A (Alrescha, al Rescha) – is Binary Star with an apparent magnitude of 4.33. This is a Giant Star that is located around 151 light years from the Solar System.
- 30 Piscium – is a solitary variable Star, visible by naked eye with an apparent magnitude of 4.37 and around 410 light years away.
Fact: the brighter the luminosity of the star the lower the apparent magnitude number.
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 Libra? –
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 stars they 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 Zodiac characters like Zeus, Pegasus and other powerful gods and goddesses like the goddess of justice.
Background & Facts:
Part of the Zodiac
The Constellation of Libra located in the Southern Sky, and also seen from the Northern Hemisphere is a medium-sized constellation of the zodiac.
When the zodiac ‘ring’ or ‘belt’, of constellations is listed in order, as the 12 astrological zodiac signs (months) of the calendar from January to December, it lists as:
In the order of the vernal equinox (where the ecliptic meets the celestial equator) the order of the signs begins with Aries, the first, and then and runs through to Pisces. In this series Libra is the 7th sign of the Zodiac.
However you categorize the list of the Constellations of the Zodiac, each Constellation in the belt, like Libra, has two immediate Constellation neighbors – one in front (e.g. Scorpio is in front of Libra and one behind it (e.g. Virgo is behind Libra).
Hiding in the house
The constellations in the Zodiac ‘belt’ form an imaginary ring that’s closely aligned to the orbit of Earth.
As a result each of the 12 zodiac constellations has a cycle that passes through the Sun (the biggest and brightest Star, that is actually a Dwarf Star not a Giant Star).
The Sun is then said to house (hide) each Constellation in turn. It houses a different Constellation each month and then you cannot see that particular Constellation.
The Sun passes through the sign of Libra between September 23 and October 23. At this point the Sun would be referred to as hiding in the house of Libra.
The neighbors of Constellation Libra
The Constellation of Libra is neighbored by several constellations in the Southern Sky:
- The large Constellation Virgo and the image of Dike, the goddess of justice holding the scales of balance is the bright guide point for finding the Constellation of Libra in the sky.
The other neighbors include:
- Centaurus; Hydra; Lupus; Ophiuchus; Scorpius, and Serpens Caput.
Within Constellation Libra
The Constellation of Libra is formed by of a number of different components.
The different components housed by the Constellations are mainly Stars, Deep Sky Objects and Messier objects (galaxies).
The best time of year to see the Stars and Deep Sky Objects in Libra is from April until June.
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
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.
Stars that host Planets
Libra has 3 named stars that host planets within the Constellation Libra that have been officially approved by the International Astronomical Union (IAU)
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 Staris 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.
Charles Messier, a French astronomer, is credited with identifying various objects in the night sky, around 1764.
He is famous for publishing the Charles Messier astronomical catalogue ‘the Messier ‘New General Catalogue’, that lists 110 nebulae and star clusters.
These later became known as the Messier objects.
Libra is not home to any messier objects, but it does contain a few faint deep-sky objects, such as:
This is a barred spiral galaxy, 83 million light years away
This object is a lenticular galaxy
This object is a globular star cluster
A spiral galaxy
An active barred spiral galaxy, 146 million light years away
An active spiral galaxy 150 million light years away
An intermediate, around 85 million years away
These are only visible with a large telescope
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 asthe NASA Spitzer Space Telescope, operated by NASA, and the famous Hubble Space Telescope.
FACT: A star cluster is a large group of Stars, of which there are 2 different types:
- 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.
What is the Milky Way?
The Milky Way is a Spiral Galaxy, containing over 200 billion Stars, and actually forms part of the Constellation of Sagittarius.
The Milky Way itself is not a Constellation of Stars.
This 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.
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 the Constellation ofSagittarius.
The Stars that make up the Milky Way are many light years away and cannot be individually identified by the naked eye.
The meteor showers
The Libra Constellation is associated with 1 meteor shower known as ‘The May Librids’.
The Librids meteor shower only occurs for a very short period from May 1st to May 9th.
It peaks around May 6th. There are around 2-3 meteors per hour.
Historical significance: the myths surrounding Constellation Libra
For thousands of years, various cultures around the world have identified and named the constellation we know and see in the night sky as Libra.
Constellation Libra is one of the oldest and medium sized Constellations of the Zodiac.
Libra was one of the first 48 Constellations listed by Ptolemy, the Greek/Roman astronomer.
The Babylonians also recorded details of variousbright stars within the constellations in their Babylonian star catalogues before 100BCE, like Libra.
The identity of Libra has been around for over 3000 years.
The Babylonians referred to Libra as ‘ZIB. BA.AN.NA’, meaning ‘the balance of heaven’.
It was also known ‘as the claws of the Scorpion’ due to its close location to the Constellation of Scorpius.
Shamash, the Sun god was also the patron of Justice, truth and morality worshipped by the Mesopotamians. They held the Scales sacred to this god.
In ancient Egypt the 3 main Stars – alpha Lib, Beta Lib and Theta Lib were viewed as the image of ‘a boat’.
There are many Greek myths and legends surrounding the origin and names of the constellations, involving gods, goddesses and even mythical creatures.
The Constellation of Libra is mainly connected with the Constellation of Virgo due to its close proximity and how the goddess of justice holds the scales.
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 Zodiac sign of Libra
The constellation of Libra is one of the 12 constellations of the Zodiac and as such is represented by the birth star sign of Libra.
We now know what Libra looks like in the night sky in the Southern Hemisphere but what are the typical personal characteristics of someone born under the zodiac sign of Libra?
The Star sign of Libra includes people born between, September 23 and October 23.
Libra is one of the cardinal air elements of the Zodiac along with Gemini and Aquarius.
It is believed that people born under one of these signs will have certain traits and behaviors.
The typical characteristics of Libran people
The typical characteristics of a Libran person, is related to having balance.
They are likely to be fair-minded with strong social skills, have charm and an artistic flair. They can also be idealistic and make good leaders and team players.
Librans are sometimes referred to as the diplomats of the Zodiac
- Negative traits: They can be self-focused but realize their value. As they seek harmony and balance they are reluctant to show their anger or displeasure and this can cause resentment.
- Positive Traits: They are typically good communicators.
They are believed to be a good judge of character and particularly sociable beings.
They love balance and focus on the good in most situations.
Fun Facts about Constellations – Did you know that?
- 42 of the Constellations have been named after animals with a story behind each name. Libra is the only Constellation of the Zodiac to be named after an object, not an animal or mythical Character.
- The Constellations are not part of the solar system; they are groups of stars that appear to form shapes that are visible from Earth.
- The largest Constellation overall is called Hydra and the smallest Constellation is called Crux.
- The largest Constellation of the Zodiac is Virgo, Aquarius is the 2nd, and Libra ranks as the 7th largest Constellation in the Zodiac.
- The Constellation of Libra is visible from both the Northern and Southern Hemispheres, when viewed without light pollution.
- 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.
- Constellations are not found in the Solar System.
- 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 Stars (cool Stars)
- Spiral Galaxies make up about two thirds of all the Galaxies in the Universe
- The Constellation of Libra can be spotted all year round in the night sky, but it is dim, with no very bright Stars.
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 was 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 do so and possibly in time the images may look very different.