Asterism (astronomy)

asterismasterismsconstellationgroup of starsastronomical asterismconstellationsFalse Cross
In observational astronomy, an asterism is a popularly-known stationary pattern or group of stars that are recognised in the night sky as viewed from Earth.wikipedia
494 Related Articles

Ursa Major

Great BearOrsa MaggioreBear
For example, the asterisms known as The Plough (Charles' Wain, the Big Dipper, etc.) comprises the seven brightest stars in the International Astronomical Union (IAU) recognised constellation Ursa Major.
Ursa Major is primarily known from the asterism of its main seven relatively bright stars comprising the "Big Dipper", "the Wagon", "Charles's Wain" or "the Plough" (among others), with its stellar configuration mimicking the shape of the "Little Dipper".

Crux

Southern CrossSouthern Cross constellationconstellation
Another is the asterism of the Southern Cross, whose recognised constellation is Crux (crux is an area of the night sky in which the Southern Cross is located).
Its name is Latin for cross, and it is dominated by a cross-shaped or kite-like asterism that is commonly known as the Southern Cross.

Constellation

constellationsEuropean constellationModern constellation
This colloquial definition makes it appear quite similar to a constellation, but they differ mostly in that a constellation is an officially recognized area of the sky, while an asterism is a visually obvious collection of stars and the lines used to mentally connect them; as such, asterisms do not have officially determined boundaries and are therefore a more general concept which may refer to any identified pattern of stars.
Other star patterns or groups called asterisms are not constellations per se but are used by observers to navigate the night sky.

Great Diamond

The Great Diamond consisting of Arcturus, Spica, Denebola, and Cor Caroli. An East-West line from Arcturus to Denebola forms an equilateral triangle with Cor Caroli to the North, and another with Spica to the South. The Arcturus, Regulus, Spica triangle is sometimes given the name Spring Triangle. Together these two triangles form the Diamond. Formally, the stars of the Diamond are in the constellations Boötes, Virgo, Leo, and Canes Venatici.
The Great Diamond is an asterism.

Arcturus

ArcturiansArcturianArcturan
The Great Diamond consisting of Arcturus, Spica, Denebola, and Cor Caroli. An East-West line from Arcturus to Denebola forms an equilateral triangle with Cor Caroli to the North, and another with Spica to the South. The Arcturus, Regulus, Spica triangle is sometimes given the name Spring Triangle. Together these two triangles form the Diamond. Formally, the stars of the Diamond are in the constellations Boötes, Virgo, Leo, and Canes Venatici.
Together with Spica and Denebola (or Regulus, depending on the source), Arcturus is part of the Spring Triangle asterism and, by extension, also of the Great Diamond along with the star Cor Caroli.

Summer Triangle

third star forms a symbolic bridge
The Summer Triangle of Deneb, Altair, and Vega — α Cygni, α Aquilae, and α Lyrae — is easily recognized in the northern hemisphere summer skies, as its three stars are all of the 1st magnitude. The stars of the Triangle are in the band of the Milky Way which marks the galactic equator, and are in the direction of the galactic center.
The Summer Triangle is an astronomical asterism in the northern celestial hemisphere.

Deneb

Alpha Cygniα CygAlpha Cygni (Deneb)
The Summer Triangle of Deneb, Altair, and Vega — α Cygni, α Aquilae, and α Lyrae — is easily recognized in the northern hemisphere summer skies, as its three stars are all of the 1st magnitude. The stars of the Triangle are in the band of the Milky Way which marks the galactic equator, and are in the direction of the galactic center. The Northern Cross in Cygnus. The upright runs from Deneb (α Cyg) in the Swan's tail to Albireo (β Cyg) in the beak. The transverse runs from Aljanah (ε Cyg) in one wing to Fawaris (δ Cyg) in the other.
It is one of the vertices of the asterism known as the Summer Triangle and forms the 'head' of the Northern Cross.

Cygnus (constellation)

Cygnusconstellation of CygnusCygnus constellation
The Summer Triangle of Deneb, Altair, and Vega — α Cygni, α Aquilae, and α Lyrae — is easily recognized in the northern hemisphere summer skies, as its three stars are all of the 1st magnitude. The stars of the Triangle are in the band of the Milky Way which marks the galactic equator, and are in the direction of the galactic center. The Northern Cross in Cygnus. The upright runs from Deneb (α Cyg) in the Swan's tail to Albireo (β Cyg) in the beak. The transverse runs from Aljanah (ε Cyg) in one wing to Fawaris (δ Cyg) in the other.
The swan is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross (in contrast to the Southern Cross).

Boötes

BootesBooAlmareth
The Great Diamond consisting of Arcturus, Spica, Denebola, and Cor Caroli. An East-West line from Arcturus to Denebola forms an equilateral triangle with Cor Caroli to the North, and another with Spica to the South. The Arcturus, Regulus, Spica triangle is sometimes given the name Spring Triangle. Together these two triangles form the Diamond. Formally, the stars of the Diamond are in the constellations Boötes, Virgo, Leo, and Canes Venatici.
The ancient Greeks saw the asterism now called the "Big Dipper" or "Plough" as a cart with oxen.

Leo (constellation)

Leoconstellation of Leoconstellation Leo
The Great Diamond consisting of Arcturus, Spica, Denebola, and Cor Caroli. An East-West line from Arcturus to Denebola forms an equilateral triangle with Cor Caroli to the North, and another with Spica to the South. The Arcturus, Regulus, Spica triangle is sometimes given the name Spring Triangle. Together these two triangles form the Diamond. Formally, the stars of the Diamond are in the constellations Boötes, Virgo, Leo, and Canes Venatici.
The lion's mane and shoulders also form an asterism known as "The Sickle," which to modern observers may resemble a backwards "question mark."

Orion (constellation)

Orionconstellation of OrionOrion constellation
This process was essentially arbitrary, and different cultures have identified different constellations, although a few of the more obvious patterns tend to appear in the constellations of multiple cultures, such as those of Orion and Scorpius.
Another name for the asterism of Alnilam, Alnitak and Mintaka is Väinämöisen vyö (Väinämöinen's Belt) and the stars "hanging" from the belt as Kalevanmiekka (Kaleva's sword).

Aquila (constellation)

AquilaAquilaeAql
The Summer Triangle of Deneb, Altair, and Vega — α Cygni, α Aquilae, and α Lyrae — is easily recognized in the northern hemisphere summer skies, as its three stars are all of the 1st magnitude. The stars of the Triangle are in the band of the Milky Way which marks the galactic equator, and are in the direction of the galactic center.
Its brightest star, Altair, is one vertex of the Summer Triangle asterism.

Hyades (star cluster)

HyadesHyades clusterHyades star cluster
e.g. Both the open clusters The Pleiades or Seven Sisters and The Hyades in Taurus are sometimes considered as an asterisms, but this depends on the source.
Four of these stars, with Bayer designations Gamma, Delta 1, Epsilon, and Theta Tauri, form an asterism that is traditionally identified as the head of Taurus the Bull.

Spica

α VirAlaezelAzimech
The Great Diamond consisting of Arcturus, Spica, Denebola, and Cor Caroli. An East-West line from Arcturus to Denebola forms an equilateral triangle with Cor Caroli to the North, and another with Spica to the South. The Arcturus, Regulus, Spica triangle is sometimes given the name Spring Triangle. Together these two triangles form the Diamond. Formally, the stars of the Diamond are in the constellations Boötes, Virgo, Leo, and Canes Venatici.
Spica, along with Arcturus and Denebola or Regulus depending on the source, is part of the Spring Triangle asterism, and by extension, also of the Great Diamond together with the star Cor Caroli.

Altair

αα AqlAlpha
The Summer Triangle of Deneb, Altair, and Vega — α Cygni, α Aquilae, and α Lyrae — is easily recognized in the northern hemisphere summer skies, as its three stars are all of the 1st magnitude. The stars of the Triangle are in the band of the Milky Way which marks the galactic equator, and are in the direction of the galactic center.
Altair is an A-type main sequence star with an apparent visual magnitude of 0.77 and is one of the vertices of the Summer Triangle asterism (the other two vertices are marked by Deneb and Vega).

Winter Hexagon

Winter Circle
One-third of the 1st-magnitude stars visible in the sky (seven of twenty-one) are in the so-called Winter Hexagon with Capella, Aldebaran, Rigel, Sirius, Procyon, and Pollux with 2nd-magnitude Castor, on the periphery, and Betelgeuse off-center. Although somewhat flattened, and thus more elliptical than circular, the figure is so large that it cannot be taken in all at once, thus making the lack of true circularity less noticeable. (The projection in the chart exaggerates the stretching.) Some prefer to regard it as a Heavenly 'G'.
The Winter Hexagon or Winter Circle/Oval is an asterism appearing to be in the form of a hexagon with vertices at Rigel, Aldebaran, Capella, Pollux, Procyon, and Sirius.

Pegasus (constellation)

PegasusPegasoPegasi
The Great Square of Pegasus is the quadrilateral formed by the stars Markab, Scheat, Algenib, and Alpheratz, representing the body of the winged horse. The asterism was recognized as the constellation ASH.IKU "The Field" on the MUL.APIN cuneiform tablets from about 1100 to 700 BC.
Alpha (Markab), Beta (Scheat), and Gamma (Algenib), together with Alpha Andromedae (Alpheratz, once also designated Delta Pegasi) form the large asterism known as the Square of Pegasus.

Gamma Pegasi

γ PegγAlgenib
The Great Square of Pegasus is the quadrilateral formed by the stars Markab, Scheat, Algenib, and Alpheratz, representing the body of the winged horse. The asterism was recognized as the constellation ASH.IKU "The Field" on the MUL.APIN cuneiform tablets from about 1100 to 700 BC.
Gamma Pegasi (γ Pegasi, abbreviated Gamma Peg or γ Peg), also named Algenib, is a star in the constellation of Pegasus, located at the southeast corner of the asterism known as the Great Square.

Vega

2828Botercadentconstellation of Vega
The Summer Triangle of Deneb, Altair, and Vega — α Cygni, α Aquilae, and α Lyrae — is easily recognized in the northern hemisphere summer skies, as its three stars are all of the 1st magnitude. The stars of the Triangle are in the band of the Milky Way which marks the galactic equator, and are in the direction of the galactic center.
This star lies at a vertex of a widely spaced asterism called the Summer Triangle, which consists of Vega plus the two first-magnitude stars Altair, in Aquila, and Deneb in Cygnus.

Betelgeuse

α OriBetelg'''euseBetelgeuse mass loss
One-third of the 1st-magnitude stars visible in the sky (seven of twenty-one) are in the so-called Winter Hexagon with Capella, Aldebaran, Rigel, Sirius, Procyon, and Pollux with 2nd-magnitude Castor, on the periphery, and Betelgeuse off-center. Although somewhat flattened, and thus more elliptical than circular, the figure is so large that it cannot be taken in all at once, thus making the lack of true circularity less noticeable. (The projection in the chart exaggerates the stretching.) Some prefer to regard it as a Heavenly 'G'. The Winter Triangle visible in the northern sky's winter and comprise the first magnitude stars Procyon, Betelgeuse and Sirius.
Betelgeuse is one of three stars that make up the Winter Triangle asterism, and it marks the center of the Winter Hexagon.

Alpha Pegasi

α PegMarkabα
The Great Square of Pegasus is the quadrilateral formed by the stars Markab, Scheat, Algenib, and Alpheratz, representing the body of the winged horse. The asterism was recognized as the constellation ASH.IKU "The Field" on the MUL.APIN cuneiform tablets from about 1100 to 700 BC.
Alpha Pegasi (α Pegasi, abbreviated Alpha Peg, α Peg), also named Markab, is the third-brightest star in the constellation of Pegasus and one of the four stars in the asterism known as the Great Square of Pegasus.

Winter Triangle

The Winter Triangle visible in the northern sky's winter and comprise the first magnitude stars Procyon, Betelgeuse and Sirius.
The Winter Triangle is an astronomical asterism formed from three of the brightest stars in the winter sky.

Big Dipper

Northern DipperPloughBeidou
For example, the asterisms known as The Plough (Charles' Wain, the Big Dipper, etc.) comprises the seven brightest stars in the International Astronomical Union (IAU) recognised constellation Ursa Major.
The Big Dipper (US) or the Plough (UK, Ireland) is a large asterism consisting of seven bright stars of the constellation Ursa Major; six of them are of second magnitude and one, Megrez, of third magnitude.

Beta Pegasi

β PegβScheat
The Great Square of Pegasus is the quadrilateral formed by the stars Markab, Scheat, Algenib, and Alpheratz, representing the body of the winged horse. The asterism was recognized as the constellation ASH.IKU "The Field" on the MUL.APIN cuneiform tablets from about 1100 to 700 BC.
It forms the upper right corner of the Great Square of Pegasus, a prominent rectangular asterism.

Northern Cross (asterism)

Northern Cross
The Northern Cross in Cygnus. The upright runs from Deneb (α Cyg) in the Swan's tail to Albireo (β Cyg) in the beak. The transverse runs from Aljanah (ε Cyg) in one wing to Fawaris (δ Cyg) in the other.
The Northern Cross is a prominent astronomical asterism in the northern hemisphere celestial sphere, corresponding closely with the constellation Cygnus The Swan.