Glossary term: Sagittarius

Description: Sagittarius is one of the constellations in the Zodiac, i.e. the stars that make up this constellation are in the part of the sky that intersects with the ecliptic (the plane defined by the Earth's orbit around the Sun). Hence, from Earth, we can regularly find the Sun, and also the other planets of the Solar System, in the constellation Sagittarius. In the case of the Sun this occurs from late December to early January (at that time, of course, we cannot see the constellation's stars). Sagittarius is one of the 88 modern constellations defined by the International Astronomical Union, but goes back much further – it was already one of the 48 constellations named by the 2nd century astronomer Claudius Ptolemy. Sagittarius is notable as the location of the center of our Milky Way galaxy and of the supermassive black hole Sagittarius A*.

Related Terms:

See this term in other languages

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

Related Media

The Milky Way arches over an African grassland. Its diffuse glow is interrupted by a stream of dark patches.

Milky Way Arch over Amboseli National Park

Caption: Winner in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   This image was taken in July 2016 from the Amboseli National Park in Kenya, located close to the equator. In Egyptian mythology from northern Africa, the Milky Way was associated with a river sailed by gods and souls. The Zulu in South Africa interpret this pattern of dark and bright clouds of stars as an animal with black and white skin, whereas the South African Khoikhoi and San considered it “The Star’s Road”. In several South African cultures, the arch of the Milky Way is a pathway to the heavens formed by a mother goddess, according to a South African creation myth that was adopted in the 19th century from early ethnological research, but has vanished today. In the middle-right of the image we find the bright red star Antares in the modern constellation of the Scorpion and at the upper-left edge is the white star Vega that is considered a Male Steenbok by the peoples around Cape Town. Indigenous Australians have many names for the Milky Way. The Yolnu people of Arnhem Land in Australia’s Northern Territory refer to the Milky Way as Milnguya, the sky river. One of the prominent patterns in this image is associated with the contrast between the light and dark regions of the Milky Way. These dark regions are cool dense clouds of interstellar dust and gas, which block the light from stars behind them. One of the prominent patterns is that of the Celestial Emu referred to as Tchingal by several Indigenous peoples of south Australia. The head and beak of the emu (the Coalsack Nebula) lie to the bottom-left of the Southern Cross (seen in the far bottom-right of the image), and the body and legs stretch leftward from it. Other indigenous groups associate the dark regions with caves or waterways. The orientation of the emu over the year provides important clues as to when it is time to pick emu eggs, and when the eggs are hatching. In some months, when these clouds of the Milky Way are close to the horizon, they are not considered as emu at all but as two creeping crocodiles. The modern figure of the dark Pipe Nebula is clearly visible above the centre of the Galaxy; the smoke of this pipe reaches the colourful rho Ophiuchi region next to Antares in Scorpius, the orange-red star just above the Milky Way. Antares is referred to by the Boorong people as Djuit, the red-rumped parrot, while the Kokatha people of the Western Desert refer to Antares as Kogolongo, the red-tailed black cockatoo. In addition, some notable constellations can be seen: Cygnus, Aquila, Lyra, Scorpius, Sagittarius, Crux, and Centaurus. The pointer stars, Alpha and Beta Centauri, are occasionally interpreted as The Eyes of the Beast in some South African traditions.
Credit: Amirreza Kamkar/IAU OAE

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

A starry sky, including the diffuse glow of the Milky Way behind a stepped mud brick pyramid.

Galaxy Arm

Caption: Honourable mention in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   Taken from the south of Iraq in January 2022, this image shows a clear sky over one of the many ancient monuments in the region which looks like a Babylonian ziggurat. The Sumerians had invented these mountain-like buildings even before the invention of script; the earliest ziggurats appear around 4000 years before the common era. They look like the frustum of a pyramid and in Babylonian times often had temples on top. Next to the stairs of the ziggurat are the constellations of the southernmost part of the Zodiac, also invented in Babylon. Today, we call them Capricorn (left, with a planet in it) and Sagittarius, whose brightest stars form the asterism of the Teapot. For the Babylonians, Sagittarius was the god Pabilsang, the city god of Larak and a god of agriculture and war. He was also the husband of the mighty goddess of medicine, Gula, and his iconography is a hybrid creature holding a bow and arrow: a male human torso and head attached to the body of a horse with four legs, two gigantic wings and two tails — a horse tail and a scorpion tail. Such a creature did not exist in Greek mythology, so the Greeks reduced it to something they knew, a centaur holding a bow and arrow. This picture still did not make sense in Greek culture because centaurs were considered wild and cruel, and not intelligent enough to use a bow and arrow. Therefore, there was another Greek figure that existed simultaneously: a man with hooves instead of feet at the ends of his legs, a satyr, but this figure vanished in Roman times.  Capricornus is one of the most stable foreign creatures in the Zodiac and has been unchanged over millennia. It is depicted as a hybrid creature with the front part of a goat and the back part of a fish. This so-called Goat-Fish constellation has been recognised since the earliest writings of astronomy in Babylon. In Babylonian religion it is a good-natured, benevolent demon that protects humans, supports all healing processes and accompanies the god of wisdom and witchcraft. The Greeks simply adopted it and invented a saga for it. In Roman times, it became tremendously famous because emperor Augustus of Rome used it as his personal symbol, also imprinting it on coins and other political propaganda tools. In Sagittarius, there is also the bright bulge of the Milky Way. That this is hardly visible in this photograph is a result of modern civilization; the huge number of artificial lights that we use on Earth also illuminates the night sky and makes it impossible to see the Milky Way in areas where humans live.
Credit: Ruqayah Mohammed/IAU OAE

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

The diffuse glow of the Milky Way broken by dark patches. Right, the red star Antares forms the top of a hook-like pattern

Milky Way Arch over La Palma

Caption: Winner in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   This image, which shows the majestic band of the Milky Way and a range of culturally significant patterns, was taken in May 2022 at a very high altitude from the Roque de los Muchachos Observatory in La Palma, from which one can see the clouds below. Some prominent star patterns include Scorpius, Sagittarius, Lyra, Cygnus, Aquila, the Summer Triangle asterism, and the Teapot asterism. As the Canary Islands used to be a starting point for European sailors to explore the world, we use this place to point to the many indigenous cultures they encountered. Most notably it is the dark patterns within the band of the Milky Way that hold significance for many Indigenous cultures around the world. The dark patterns are in fact dense, cool clouds of gas and dust that block the light from stars. Indigenous people see caves, waterways and various patterns associated with the dark regions of the Milky Way. The constellations and patterns hold different cultural significance and interpretations for different people. For example, the constellation Scorpius is referred to by Polynesian people as the demigod Maui’s Fishhook. The Yolnu people of Arnhem Land associate Scorpius with a crocodile called Ingalpir. Some Indigenous Australian groups associate stories with individual stars within Scorpius, most notably Antares, the orange-red star in the top right of the image above the band of the Milky Way. Next to the Scorpion and above the bright centre of the Milky Way, there is a prominent dark cloud that is called the Pipe Nebula by modern astrophotographers. The smoke of this pipe goes up to rho Ophiuchi. This and all the other dark clouds in the Milky Way together form the backbone of heaven for some tribes, and an animal with black-and-white skin for South African Zulu people. The nomenclature of bright stars also has cross-cultural roots. For example, Vega (the bright blue star towards the top of the image) comes from the Arabic waqi, from al-nasr al-waqi, the Eagle who throws himself down (in order to hunt). This contrasts with the Flying Eagle, Altair, also derived from Arabic. Antares is a Greek word meaning “the one similar to Mars”, referring to its colour. The star name Shaula in the stinger of the Scorpion is a modern version of the Babylonian or even Sumerian star name.
Credit: Amirreza Kamkar/IAU OAE

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

The Milky Way arches over a mountain-top building. Its diffuse glow is broken by dark patches and is brighter on the right

The Moon and Milky Way arch Above the Golden Hall

Caption: Winner in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   Taken in April 2021 from the top of the Laojun Mountain in China, this image shows a panoramic view of the Milky Way over the Golden Hall called “Yuhuangding” as a symbol of wealth. In China, the Milky Way is considered a huge stream like one of the big rivers. It separates the Cowherd (Altair) and his beloved Weaving Girl (Vega) and it has a Celestial Ford in the northern dark cloud in the modern constellation Cygnus. The Milky Way appears as a whitish arch as we cannot distinguish all the individual stars, but instead see the accumulation of light from them. It is a disc-shaped galaxy and the Solar System is located within one of its spiral arms, so we see it from inside, which gives it the shape of a band in our sky. It is associated with the religions and mythologies of several cultures. The modern term Milky Way derives from Greek folklore as the milk spread in the sky by the mother goddess Hera, when she unwillingly breastfed young Heracles. This son of Zeus and a mortal woman was put next to her while she was asleep but from his strong sucking she woke up and realised she was feeding an unknown child, and immediately pushed the child away. Greek philosophers like Plato considered the glittering band in the sky to be the traces of a former path of the Sun. Alternatively, for the Tupi-Guarani indigenous mythology from South America, the Milky Way represents the “path of tapir”. For some Australian native peoples, its dark clouds formed the shape of an emu if high in the sky, and of crocodiles if low on the horizon. For many southern African, South American and Australian cultures, it was considered a pathway to or from heaven. At the right edge of the image, we can recognise the modern constellation Scorpius with its most prominent star, Antares, the reddish star just above the Milky Way. The brightest point seen in the centre bottom of the image is the rising Moon with Jupiter next to it. A few constellations can be distinguished in this image, including Corona Australis, a faint arc-shaped constellation located to the bottom right. Just above the Southern Crown, we can see the Teapot asterism as part of the Sagittarius constellation. Since Sagittarius lies next to the centre of the Milky Way, many structures such as star-forming regions, globular clusters and planetary nebulae can be found within its boundaries. In Sagittarius, we also find a supermassive black hole four million times as massive as our Sun. At the left side of the band, we can identify the bright star Deneb in the constellation Cygnus, The Swan, through which the Milky Way runs, meaning that a variety of star clusters are found in this constellation.
Credit: Likai Lin/IAU OAE

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

The bright Moon is reflected in a pool of water. The diffuse light and dark patches of the Milky Way dominate the top right

Lyrid of the Lake

Caption: Winner in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   Taken in the early hours of 24 April 2022, this image captures the sky of Yunnan Province, China, with a reflection on Lake Nian. The Milky Way is visible on the left side, while whitish Earth clouds are visible on the right. A Lyrid meteor crosses the sky along the Milky Way, its tail pointing back toward the shower's radiant in the constellation Lyra, which lies outside the image above the upper edge. The natural colours of the meteor are impressively clear. A few constellations are also visible. In the top left corner we can recognise the small constellation of the Dolphin, in which five brightest stars comprise the asterism. This asterism forms the head-part of the larger Greek constellation of the Dolphin and was considered the Dolphin since Roman times, when Ptolemy formed the new constellation of Equuleus in the southern part of the original figure. In mediaeval China, this asterism was considered the Good and the Rotten Gourd, the good one being formed by the brighter rhombus on the top and the rotten one made of faint stars in the tail of the Roman dolphin. The bright star to the right of the Dolphin and at the top of the image is Altair, the brightest star in the constellation Aquila. In Chinese uranology, Altair, together with some adjacent areas, forms the constellation of the Drum at the River. However, in Chinese folklore, the bright star stands for a boy in love with a girl, who is represented by the bright star Vega (in Lyra) on the other side of a huge celestial stream, the Milky Way. Vega is not visible in this image but the Lyrid meteor is like a teardrop of the unlucky girl who cannot reach her lover. In the upper right of the image, the constellation Scorpius shines with its bright reddish star Antares. With some of its neighbouring stars, it was regarded in China as the asterism of The Heart, which was also one of the Lunar Mansions. It was considered the heart of the Azure Dragon, the super-constellation of spring, in ancient China. Scorpius and Sagittarius, in the middle of the image, contain the brightest clouds of the Milky Way, the Galactic Centre, which also has clearly visible dark clouds in front of the bright ones. There is no classical Greco-Roman constellation between Aquila and Scorpius, but in the 17th century, two Polish astronomers, the couple Jan and Elizabeta Hevelius, named this area of bright clouds in the Milky Way Scutum, the Shield, in memory of a Polish king. In China, however, this area directly outside the super-constellation (or heavenly enclosure) of the Celestial Market Place was seen as depicting Market Officers.
Credit: Jianfeng Dai/IAU OAE

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons