Sagittarius, the Archer (Sgr)
(SAJ-ih-TARE-ee-us)
The Southern constellation of Sagittarius, the Archer, is best viewed in Summer during the month of August.
Sagittarius is the 15th largest constellation. It's brightest star is Kaus Australis at magnitude 1.79. The boundary of the Sagittarius constellation contains 22 stars that host known exoplanets.
Ross?154 is the 9th closest star to Earth at 9.7 light years.
- Pronunciation:
- SAJ-ih-TARE-ee-us
- Meaning:
- Archer
- Genitive:
- Sagittarii
- Abbreviation:
- Sgr
- Asterism:
- Teapot
- Constellation Family:
- Zodiacal
- Hemisphere:
- Southern
- Quadrant:
- SQ4
- Visibility:
- 55° N - 90° S
- Best viewing month*:
- August
- Area:
- 867 sq. degrees
- Size:
- 15th largest
- Right Ascension (avg):
- 19h 23m
- Declination (avg):
- -26°
- Brightest star:
- Kaus Australis (1.79)
- Stars with planets:
- 22
Brightest Stars in Sagittarius
The 10 brightest stars in the constellation Sagittarius by magnitude.
- Star
- Magnitude
- Spectral class
- Epsilon Sagittarii (ε Sgr)
- 1.79
- B9.5III
- Sigma Sagittarii (σ Sgr)
- 2.05
- B2.5V
- Zeta Sagittarii (ζ Sgr)
- 2.6
- A3IV
- Delta Sagittarii (δ Sgr)
- 2.72
- K3III
- Lambda Sagittarii (λ Sgr)
- 2.82
- K1IIIb
- Pi Sagittarii (π Sgr)
- 2.88
- F2II/III
- Gamma Sagittarii (γ2 Sgr)
- 2.98
- K0III
- Eta Sagittarii (η Sgr)
- 3.1
- M2III
- Phi Sagittarii (φ Sgr)
- 3.17
- B8.5III
- Tau Sagittarii (τ Sgr)
- 3.32
- K1/K2III
Star Clusters in Sagittarius
The most notable and easy-to-find star clusters in the constellation Sagittarius . Also see all star clusters.
- Star cluster
- Catalog #
- Cluster type
- ESO 456-78
- globular
- Messier 18
- M18
- open
- Messier 21
- M21
- open
- Messier 23
- M23
- open
- Messier 24
- M24
- open
- Messier 25
- M25
- open
- Messier 28
- M28
- globular
- Messier 55
- M55
- globular
- Messier 69
- M69
- globular
- Messier 70
- M70
- globular
- Messier 75
- M75
- globular
- NGC 6440
- globular
- NGC 6522
- globular
- NGC 6528
- globular
- NGC 6540
- globular
- NGC 6544
- globular
- NGC 6553
- globular
- NGC 6558
- globular
- NGC 6569
- globular
- NGC 6624
- globular
- NGC 6638
- globular
- NGC 6642
- globular
- NGC 6652
- globular
- NGC 6717
- globular
- NGC 6723
- globular
- Palomar 8
- globular
- Sagittarius Cluster
- M22
- globular
- Terzan 5
- globular
Nebulae in Sagittarius
Notable and easy-to-find nebulae in the constellation Sagittarius. Also see all nebulae.
- Nebula name
- Catalog #
- Nebula type
- Barnard's Bubble Nebula
- diffuse
- Eye of Sauron Nebula
- planetary
- Inkspot Nebula
- dark
- Lagoon Nebula
- M8
- emission
- Little Gem Nebula
- planetary
- Omega Nebula
- M17
- H II region
- Pistol Nebula
- H II region
- Red Spider Nebula
- planetary
- Trifid Nebula
- M20
- H II region
- Parrot’s Head Nebula
- dark
Galaxies in Sagittarius
The most notable galaxies in the constellation Sagittarius. Also see all galaxies.
- Name
- Alt name
- Type
- Barnard's galaxy
- C57
- irregular
- Kowal's Object
- dwarf
- Sagittarius Dwarf
- dwarf
- Tinker Bell Triplet
- galaxy group
Milky Way Satellites in Sagittarius
Dwarf satellite galaxies that orbit the Milky Way Galaxy located in the constellation Sagittarius. Also see all Milky Way satellite galaxies.
- Galaxy name
- Alt name
- Magnitude
- Sagittarius Dwarf
- 4.5
- Sagittarius II
Neutron Stars in Sagittarius
These are the most well-known neutron stars in the constellation Sagittarius. Although neutron stars cannot be seen in any amateur telescope, they are at the center of many supernova remnant nebulae, which can be seen. Also see all neutron stars.
Black Holes in Sagittarius
These are the most well-known smaller (non-supermassive) black holes in the constellation Sagittarius. Although black holes cannot be seen directly, the smaller ones are at the center of some star clusters and supernova remnant nebulae, which can be seen. Supermassive black holes are at the center of most galaxies, such as Sagittarius A* at the center of our Milky Way galaxy. Also see all black holes.
- Black hole
- Type
- GCIRS 13E
- intermediate
- Sagittarius A*
- supermassive
- V4641 Sgr
- stellar
The Archer of the Cosmos
Designated as 'The Archer,' Sagittarius is a zodiacal constellation brimming with a multitude of astronomical gems. It's situated toward the center of the Milky Way, making it a spectacular constellation filled with nebulae, star clusters, and galaxies.
Historical Background
Sagittarius is one of the oldest recognized constellations, with origins dating back to ancient Mesopotamia. The Greeks pictured Sagittarius as a centaur wielding a bow, an image passed to the Romans and the western world. It is listed among the 48 constellations identified by the 2nd-century Greek astronomer Ptolemy, and it continues to be one of the 88 modern constellations recognized by the International Astronomical Union.
Location and Visibility
Situated in the southern sky, Sagittarius is surrounded by constellations such as Scorpius, Ophiuchus, and Capricornus. It is ideally located for observation during northern summer and southern winter. Despite being a large constellation, spanning about 867 square degrees, the constellation's main stars are relatively faint, but its distinctive 'Teapot' asterism and proximity to the Milky Way center make it easier to spot.
Notable Stars in Sagittarius
The main stars of Sagittarius form an easily recognizable asterism known as 'The Teapot.' The brightest star, Epsilon Sagittarii or Kaus Australis, forms the base of the Teapot and has an apparent magnitude of 1.79. It's a binary system around 143 light-years away. Sigma Sagittarii or Nunki, the second-brightest star in the constellation, is a blue-white star approximately 228 light-years from Earth.
Deep Sky Objects
Sagittarius is rich with deep-sky objects, thanks to its location towards the Milky Way's dense center. It houses Messier objects such as M8 (the Lagoon Nebula), M17 (the Omega Nebula), and M20 (the Trifid Nebula), all of which are notable for their stunning beauty and complexity. Additionally, Sagittarius contains the Sagittarius Dwarf Elliptical Galaxy and the Sagittarius Star Cloud, providing astronomers with plenty of objects to study.
The Galactic Center
Sagittarius holds special significance as it points towards the Galactic Center, the rotational center of the Milky Way. Located in the direction of Sagittarius, the galactic center is home to a supermassive black hole known as Sagittarius A*. This region is obscured by interstellar dust, but it can be observed using radio, infrared, and X-ray telescopes.
Observation
Locating Sagittarius involves finding its distinctive 'Teapot' shape. The spout of the teapot points towards the heart of the Milky Way, creating an awe-inspiring sight in dark skies. Binoculars or a small telescope will reveal the numerous nebulae and star clusters hidden within its borders. Keep in mind that light pollution can significantly hinder the viewing experience, so darker, more rural locations are best for observation.
Conclusion
Sagittarius, the Cosmic Archer, is a constellation that combines rich historical significance with a treasure trove of celestial objects. From its dense clusters of stars and nebulae to the supermassive black hole lurking in the Milky Way's center, Sagittarius offers a window into the universe's complexities and vastness. This constellation stands as a testament to the beauty and wonder that the night sky holds for those who take the time to look up and explore.
* Constellation shown for northen hemisphere skies. For the southern hemisphere, constellations appear rotated 180 degrees (upside-down and left-right reversed) from what is shown. Remember that seasons are reversed too - summer in northern latitudes is winter in southern latitudes.
** Circumpolar constellations are visible year-round in the hemisphere listed (and not at all in the opposite hemisphere).