Sagitta Constellation aka The Arrow
Sagitta constellation is located in the northern sky. It is also called “the Arrow.” The Greeks recognized it in ancient times and associated it with their mythology. Ptolemy included it in the Almagest. The International Astronomical Union (IAU) also listed it as one of the 88 modern constellations that we have today.
Sagitta occupies an area of about 80 square degrees or only 0.194% of our entire sky! We can really see the difference if we compare it to the area of the largest constellation (Hydra) which is 1,303 square degrees. With that, Sagitta ranks as the third smallest constellation after Equuleus and Crux. The stars that made up this constellation are not that bright and no meteor showers are associated with it.
Some people may confuse the constellation of Sagitta with the more famous zodiac constellation of Sagittarius. Though their names are somewhat related, they are two separate constellations.
Sagitta is “the Arrow” while Sagittarius is “the Archer.” Aside from that, the constellation of the Arrow is much smaller than that of the Archer’s. Sagitta ranks 86th in terms of size out of the 88 modern constellations while Sagittarius is in 15th place.
One mythology related to Sagitta is that of Hercules. They belong to the Hercules family of constellations together with Aquila the Eagle, Ara the Altar, Centaurus the Centaur, Corona Australis the Southern Crown, Corvus the Crow, Crater the Cup, Crux the Southern Cross, Cygnus the Swan, Hydra the Female Water Snake, and Lupus the Wolf. Other members of the family are Lyra the Lyre, Ophiuchus the Serpent Bearer, Scutum the Shield, Sextans the Sextant, Serpens the Serpent, Triangulum Australe the Southern Triangle, and Vulpecula the Fox.
What’s In A Name?
The name Sagitta is from Latin, meaning “the Arrow.” But before that, it was called by different names in different parts of the world. What is fascinating is that people from the past interpreted it in the same way and associated it with the same thing, the arrow.
Sagitta constellation was called Oisto by the Greeks while it went by the name al-sahm in Arabic. This Arabic name became the basis for the name of one of its stars, Sham (Alpha Sagittae). It was the Romans that gave this constellation the name Sagitta as we know it today. And even if it had different names back then, they all translate to “the Arrow.”
What Does Sagitta Look Like?
The small constellation of Sagitta is primarily outlined by four stars. The stars that make up its arrow form are Alpha Sagittae, Beta Sagittae, Delta Sagittae, and Gamma Sagittae. Gamma Sagittae is the brightest star in this constellation and is often depicted as the one that marks the arrow’s head. We can easily remember Sagitta’s form because of its somewhat Y shape!
Some sources have five stars in Sagitta’s outline, with Eta Sagittae as the arrow’s head.
Where To See the Sagitta Constellation
The constellation Sagitta is in the northern hemisphere of the celestial sphere. It lies in the fourth quadrant (NQ4) at about 20 hours right ascension and 20° north declination. It is visible between latitudes +90° and -70° from here on Earth. Everyone can see the Sagitta constellation wherever they are in the world, except in areas further south near Antarctica.
Sagitta and Its Neighbors
Sagitta is bordered by four bigger constellations. Located east of Sagitta is the constellation of Delphinus (the Dolphin). We can see Vulpecula (the Fox) to its north, Hercules (the Kneeler) to its west, and Aquila (the Eagle) to its south.
When To See the Sagitta Constellation
The constellation of the celestial arrow is not visible all year round. It is a seasonal constellation that we can see best in late summer. Specifically, we can spot this small constellation at 9 pm in August. Other constellations that we can see this month in the northern sky are Lyra the Lyre and Aquila the Eagle.
Sagitta and Its Stars
Sagitta does not have many bright stars and none of them is brighter than the third magnitude. The International Astronomical Union (IAU) has formally named three of its stars. They were given the name Sham, Sansuna, and Uruk. Two stars in this constellation are discovered to host planets. The genitive for Sagitta is Sagittae. It is abbreviated as Sge, like α Sge for example.
Aside from the ones mentioned here, other interesting stars in the constellation of Sagitta are FG Sagittae, 15 Sagittae, HD 231701, U Sagittae, WZ Sagittae, and WR 124.
1. Sham (α Sagittae)
Sham is the third brightest star in the constellation of Sagitta. It is called Alpha Sagittae in the Bayer designation. This star marks one of the fins of the celestial arrow. The stellar classification of this yellow giant is G1 II. Its apparent magnitude is +4.38 so we can see it in the naked eye. It radiates with a luminosity 340 times that of the Sun. It is
The formal name of this star is from the Arabic al-sahm, meaning “arrow.” Sham lies at a distance of about 382 light-years from our Sun.
2. Beta Sagittae (β Sagittae)
Beta Sagittae is a giant star that has undergone an evolution. Its stellar classification is G8 IIIa. With an apparent magnitude of 4.38, we can see it in the naked eye under good sky conditions. Beta Sagittae radiates at a brightness of 392 Suns and has a mass 4.33 times that of the Sun’s. It marks one of the fins (fletching) of Sagitta the Arrow.
The age of this star is said to be around 129 years old. It lies about 470 light-years away from the solar system and is moving closer to it.
3. Gamma Sagittae (γ Sagittae)
Gamma Sagittae is a single star with an apparent magnitude of +3.47. It is the brightest star in the constellation of the celestial arrow, Sagitta. This is either a K-type or an M-type giant star. It is more luminous than the Sun by about 562 times. Gamma Sagittae is approximately 2.35 billion years old and is about 258 light-years away from our Sun.
4. Delta Sagittae (δ Sagittae)
Delta Sagittae is a variable star with an apparent magnitude ranging from 3.75 to 3.83. It is a spectroscopic binary with an M-type primary component and a B-type secondary. They complete their orbit in about 10 years. This system is about 430 light-years away from Earth.
5. Epsilon Sagittae (ε Sagittae)
Epsilon Sagittae is a giant star with G8 IIIvar as its stellar classification. It is a variable star with an amplitude of 0.03 magnitudes. Its apparent magnitude changes between +5.64 to +5.67. This star has a mass about three times that of the Sun’s. It lies about 580 light-years away from the Sun.
A companion was discovered in Epsilon Sagittae, making it an optical binary. This companion is an 8th magnitude giant that is about 7,000 light-years distant from our planet.
6. Zeta Sagittae (ζ Sagittae)
Zeta Sagittae is a multiple star system with three components. It is about 326 light-years away. The combined apparent magnitude of the system is about +5.00. The components of this star system are designated Zeta Sagittae A, B, and C. Components A and B are a visual binary.
The primary, component A, has a stellar classification of A3V. It has an oblate shape because it is a fast spinner. Being the primary star, it is the brightest of the three, having an apparent magnitude of 5.64. Components B and C have an apparent magnitude of 6.04 and 9.01 respectively.
7. Eta Sagittae (η Sagittae)
Eta Sagittae is a giant star of K2 III stellar classification. It is more luminous than the Sun by 25.7 times. The apparent magnitude of this orange giant is about +5.09. It has a mass 1.7 times that of the Sun’s. Eta Sagittae is a red clump that lies 160 light-years away from the Sun.
8. Theta Sagittae (θ Sagittae)
Theta Sagittae is a double star with an apparent magnitude of +6.0. The components of this pair are 502 astronomical units away from each other. The primary component is an F-type star with a mass 1.52 times that of the Sun’s. It radiates with a brightness of 4.0 solar luminosities. Theta Sagittae is about 147 light-years distant from the Sun.
9. 9 Sagittae
The supergiant star 9 Sagittae has a stellar classification of O8e. It is a variable star with an apparent magnitude of 6.24. The radius of this star is 61.75 times that of the Sun’s. This supergiant is the Flamsteed designation of this star. Other names for it are QZ Sagittae and HD 188001. This blue-white star lies 14,174 light-years away from our Sun.
10. 15 Sagittae
15 Sagittae is a main-sequence star. It is considered a solar analog or a star that is similar to our Sun. The stellar classification of 15 Sagittae is G0V. It is 58 light-years away from our Sun. A brown dwarf was discovered to be orbiting around this star.
11. R Sagittae
R Sagittae is a G-type supergiant. It is a variable star whose apparent magnitude ranges from 8.0 to 10.5. Specifically, it was classified as a member of the RV Tauri variables. It was discovered by British astronomer Joseph Baxendell. It lies at a distance of 8,100 light-years.
12. S Sagittae
S Sagittae is a variable star whose magnitude varies from 5.24 to 6.04 in a period of 8.382 days. It is Classical Cepheid with a spectral type varying between F6Ib and G5Ib. Its radius is 58.5 times the solar radius. It is also more massive than the Sun by about seven times. This supergiant is about 2,000 light-years away from us.
13. V Sagittae
V Sagittae is a binary star system. It is one of the cataclysmic variables, stars whose brightness largely increases and then go back to its normal value. The components of this system are a main-sequence star and a white dwarf. They have an orbital period of 0.514 days.
V Sagittae has continually brightened over time and is expected to become one of the brightest points in the Milky Way when it becomes a nova.
14. HD 183143
HD 183143 is a Be star with an apparent magnitude of 6.86. This blue hypergiant is a variable star. It is also known as HT Sagittae. It is about 7,900 light-years distant.
Planets in the Arrow’s Constellation
Planetary systems are discovered in the constellation of Sagitta. Jupiter-like planets were observed in two of its stars.
HD 231701 b
HD 231701 b is an exoplanet that orbits the star Uruk (HD 231701) in Sagitta constellation. Uruk is an F-type star in the main sequence. This planetary system is 356 light-years distant from Earth.
The exoplanet HD 231701 b was formally given the name Babylonia. It is a gas giant with a mass of 1.13 Jupiters. It orbits Uruk in a period of 141.6 days.
HAT-P-34 b
HAT-P-34 b is an exoplanet orbiting the star Sansuna (HAT-P-34). This is an F-type star in the constellation of Sagitta. HAT-P-34 b is a gas giant with a mass of 3.33 Jupiters. It has an orbital period of 5.5 days. This planetary system is 819 light-years from us.
Deep-sky Objects in Sagitta Constellation
One Messier object is discovered in the constellation of the celestial arrow. Together with it are many planetary nebulae. It is interesting to remember that even if a planetary nebula has the word “planet”, it is not related to any planetary system. These deep-sky objects were given such names because they looked like planets to astronomers in the past.
Messier 71
M71 is designated NGC 6838 in the New General Catalogue. This globular cluster is around 9 to 10 billion years old. It was thought to be an open cluster before because its stars have an abundance of metals. It is about 27 light-years across.
Philippe Loys de Chéseaux discovered this deep-sky object in 1745. It has a brightness of 13, 200 Suns. M71 is 13,000 light-years away from us.
NGC 6886
NGC 6886 is a planetary nebula about 4,900 to 17,900 light-years distant. The apparent magnitude of this celestial object is 11.8 so we need a mid-level telescope to spot it in the night sky.
The central star of NGC 6886 is less massive than the Sun but is more luminous than it. It radiates at 142,000 K surface temperature. This planetary nebula was discovered in 1884 by English astronomer Ralph Copeland.
Necklace Nebula
The Necklace Nebula is a planetary nebula with a ring-like shape. It was previously a close binary. When one of the stars came close to the other, it swallowed its companion.
The smaller star inside remained in orbit, increasing the rotation rate of the bigger star. Because of this fast rotation, the star’s outer layers expanded into space. It resulted in the notable ring of this celestial object. It is about 15,000 light-years away from us.
IC 4997
IC 4997 is another planetary nebula in the constellation of Sagitta. It is a 10th magnitude object. From here on Earth, this is just a small dot in the night sky that we might think is a star. It is a variable and young nebula that is about 8,000 light-years away from us.
Mythology Related to Sagitta Constellation
People have associated at least three stories to the celestial arrow. Two of which are related to Hercules while the third one is about the god of archery Apollo. The Greeks considered Sagitta as the arrow used by Hercules to help Prometheus. A newer one suggested by Richard Hinckley Allen linked it to one of the twelve labours of Hercules. The Greek polymath Eratosthenes related it to Apollo.
Hercules Rescued Prometheus
Prometheus was a master craftsman who created humankind out of lumps of clay. He loved his creations so much that he stole fire for them from Hephaestus. This made Zeus angry. He chained Prometheus on a rock where an eagle tormented him and ate his liver. Prometheus’s liver grew back every night only to be gnawed again by the eagle the next day. He suffered like this for a long time!
The other gods felt sorry for Prometheus and asked Zeus to forgive him. The king of the gods was hesitant but offered to release him on one condition: to tell him a secret that no one else knew. Having no other choice, Prometheus revealed that Thetis, a sea nymph, would bear a child that could become very powerful. Zeus was convinced that this was indeed good information. He called for Hercules to release Prometheus.
Hercules rescued Prometheus by shooting the demented eagle and the chains. Prometheus was finally free and grateful. He would, later on, help Hercules on one of his labours.
The arrow that Hercules shot to kill the eagle was associated with the constellation of Sagitta. The eagle was also placed in the sky as the Aquila constellation.
Hercules and His Sixth Labour
The sixth labour of Hercules (Heracles) involved the vicious Stymphalian birds. They were no extraordinary creatures because they are man-eating birds. Their dung also pose threat as it was toxic. This seemed like an impossible task for Hercules because he could not go far into where they.
Athena saw his struggle and gave him a rattle (like the castanets) that he would use to scare the birds off. When he clashed the rattle, the birds flew out of the trees and into the air. This gave Hercules a chance to shoot them with his bow and arrow.
The arrow that Hercules shot in his sixth labour was one of the stories related to the constellation of Sagitta.
Apollo Slew the Cyclopes
The Cyclopes were one-eyed giants who possess extraordinary strength. The three brothers were imprisoned by their father Uranus and later on freed by Zeus. Because of their great size and strength, they were skilled at forging the weapons of the gods. They have provided Zeus his thunderbolt.
Meanwhile, Apollo and Cronis had a son named Asclepius. Asclepius was considered the ancient god of medicine because of his exceptional healing ability. He became so good at it that he can even bring people back from the dead!
This did not amuse Zeus. The god thought that this would mess with the balance of the world so he used his thunderbolt to kill Asclepius.
Apollo was enraged when he heard about what happened to his son. He wanted to avenge Asclepius’s death by killing the Cyclopes who made the thunderbolt that killed his son. Apollo shot them with his bow and arrow.
It is then interpreted that constellation Sagitta is the arrow that Apollo used to slay the Cyclopes. Asclepius was also put in the sky as the constellation Ophiuchus.
A lesser-known story related to Sagitta is that of Zeus and Ganymede. In that story, the god of love Eros shot Zeus with his arrow which made the king of the gods fall in love with the young man. Ganymede was abducted by an eagle and brought to Mount Olympus to become a cupbearer. He was then placed in the night sky as the Aquarius constellation.