A little constellation in the northern sky is called Triangulum. Its three brightest stars, which together form a long, thin triangle, gave rise to its name, which is Latin for "triangle." Triangulum, one of the forty-eight constellations recorded by the 2nd-century scientist Claudius Ptolemy, was known to the ancient Babylonians and Greeks. Six of the stars in the constellation were given Bayer labels by the celestial cartographers Johann Bayer and John Flamsteed when they catalogued its stars.
The triangle's base is made up of the white stars Beta and Gamma Trianguli, which have apparent magnitudes of 3.00 and 4.00, respectively, while its apex is made up of the yellow-white Alpha Trianguli, which has a magnitude of 3.41. Triangulum contains three-star systems with known planets, including the prominent double star system Iota Trianguli. The Triangulum Galaxy, also known as Messier 33 and a member of the Local Group, is the brightest and closest galaxy in the constellation. Within the limits of the Triangulum is also 3C 48, the first quasar is ever seen. |
History and Mythology
Triangulum and Gamma Andromedae together up the constellation known as MULAPIN (𒀯𒀳), or "The Plough," in the Babylonian star catalogues. It is famous for being the first constellation to appear on (and give its name to) a pair of tablets known as the MUL.APIN, was constructed approximately 1000 BC and contained canonical star lists. The Plough is the first constellation along the "Way of Enlil"—the northernmost quarter of the Sun's course, or the 45 days on either side of the summer solstice. It signalled the start of spring ploughing in Mesopotamia when it first appeared in the dawn sky (heliacal rising) in February. (Rogers 1998)
Triangulum was given the name Deltoton (Δελτωτόν) by the Ancient Greeks because the constellation resembled the Greek letter delta (Δ), which is capitalised. Roman scribes transliterated it, and later it was Latinized as Deltotum. (Allen 1963) While Roman author Hyginus connected it to Sicily's triangular island, once known as Trinacria due to its shape, Eratosthenes connected it to the Nile Delta. It was also known as Sicilia, according to the Romans, who thought Sicily's patron goddess Ceres pleaded with Jupiter to put the island in the heavens. (Allen 1963) Trigonon (Τρίγωνον), a term used by Greek astronomers like Hipparchos and Ptolemy, was eventually Romanized as Trigonum. Tricuspis and Triquetrum are other names for this form. (Allen 1963) The Arabic name for the Alpha and Beta Trianguli was Al Mīzān, which translates to "The Scale Beam." Gamma Andromedae and its neighbours, Beta, Gamma, and Delta Trianguli were dubbed Teen Ta Tseang Keun (天大将军, "Heaven's great general") in Chinese astronomy because they symbolised honour in astrology and a great general in myth. (Olcott 2004)
Later, the constellation Triplicitas and Orbis terrarum tripertitus—named after the three continents of Europe, Asia, and Africa—were given by the German celestial mapper Johann Bayer in the 17th century. To distinguish it from Triangulum Australe, the Southern Triangle, it was given the name Triangulus Septentrionalis. (Allen 1963) In his 1690 Firmamentum Sobiescianum, Polish astronomer Johannes Hevelius removed three dim stars—, 10 and 12 Trianguli—to create the new constellation of Triangulum Minus, renaming the original Triangulum Majus. When the constellations were created in the 1920s, the International Astronomical Union (IAU) did not recognise the smaller constellation. (Garfinkle 1997)
Triangulum and Gamma Andromedae together up the constellation known as MULAPIN (𒀯𒀳), or "The Plough," in the Babylonian star catalogues. It is famous for being the first constellation to appear on (and give its name to) a pair of tablets known as the MUL.APIN, was constructed approximately 1000 BC and contained canonical star lists. The Plough is the first constellation along the "Way of Enlil"—the northernmost quarter of the Sun's course, or the 45 days on either side of the summer solstice. It signalled the start of spring ploughing in Mesopotamia when it first appeared in the dawn sky (heliacal rising) in February. (Rogers 1998)
Triangulum was given the name Deltoton (Δελτωτόν) by the Ancient Greeks because the constellation resembled the Greek letter delta (Δ), which is capitalised. Roman scribes transliterated it, and later it was Latinized as Deltotum. (Allen 1963) While Roman author Hyginus connected it to Sicily's triangular island, once known as Trinacria due to its shape, Eratosthenes connected it to the Nile Delta. It was also known as Sicilia, according to the Romans, who thought Sicily's patron goddess Ceres pleaded with Jupiter to put the island in the heavens. (Allen 1963) Trigonon (Τρίγωνον), a term used by Greek astronomers like Hipparchos and Ptolemy, was eventually Romanized as Trigonum. Tricuspis and Triquetrum are other names for this form. (Allen 1963) The Arabic name for the Alpha and Beta Trianguli was Al Mīzān, which translates to "The Scale Beam." Gamma Andromedae and its neighbours, Beta, Gamma, and Delta Trianguli were dubbed Teen Ta Tseang Keun (天大将军, "Heaven's great general") in Chinese astronomy because they symbolised honour in astrology and a great general in myth. (Olcott 2004)
Later, the constellation Triplicitas and Orbis terrarum tripertitus—named after the three continents of Europe, Asia, and Africa—were given by the German celestial mapper Johann Bayer in the 17th century. To distinguish it from Triangulum Australe, the Southern Triangle, it was given the name Triangulus Septentrionalis. (Allen 1963) In his 1690 Firmamentum Sobiescianum, Polish astronomer Johannes Hevelius removed three dim stars—, 10 and 12 Trianguli—to create the new constellation of Triangulum Minus, renaming the original Triangulum Majus. When the constellations were created in the 1920s, the International Astronomical Union (IAU) did not recognise the smaller constellation. (Garfinkle 1997)
Characteristics
Triangulum, a minor constellation, is bounded to the north and west by Andromeda, to the west and south by Pisces, to the south by Aries, and to the east by Perseus. Between Gamma Andromedae and Alpha Arietis, the constellation's centre is located. (Simpson 2012) The constellation is known by the three-letter abbreviation "Tri," which was chosen by the IAU in 1922. (Russell 1922) Eugène Delporte, a Belgian astronomer, established the official constellation borders in 1930, which are represented by a polygon with fourteen segments. These borders' right ascension coordinates in the equatorial coordinate system range from 01h 31.3m to 02h 50.4m, while their declination coordinates range from 25.60° to 37.35°. Triangulum, which occupies 132 square degrees and 0.320 percent of the night sky, is the 78th-largest constellation out of eighty-eight. (Bagnall 2012)
Triangulum, a minor constellation, is bounded to the north and west by Andromeda, to the west and south by Pisces, to the south by Aries, and to the east by Perseus. Between Gamma Andromedae and Alpha Arietis, the constellation's centre is located. (Simpson 2012) The constellation is known by the three-letter abbreviation "Tri," which was chosen by the IAU in 1922. (Russell 1922) Eugène Delporte, a Belgian astronomer, established the official constellation borders in 1930, which are represented by a polygon with fourteen segments. These borders' right ascension coordinates in the equatorial coordinate system range from 01h 31.3m to 02h 50.4m, while their declination coordinates range from 25.60° to 37.35°. Triangulum, which occupies 132 square degrees and 0.320 percent of the night sky, is the 78th-largest constellation out of eighty-eight. (Bagnall 2012)
Deep-sky Objects
Main stars - 3
Bayer stars - 14
Stars with planets - 3
Stars brighter than magnitude 3.00 - 0
Stars within 32 Ly - 0
Messier objects - 1
Meteor showers - None
Bordering
constellations
- Messier 33 (M33) – Triangulum Galaxy (Spiral Galaxy)
- NGC 925 – Barred Spiral Galaxy
- NGC 672 – Spiral Galaxy
- NGC 784 – Barred Spiral Galaxy
Main stars - 3
Bayer stars - 14
Stars with planets - 3
Stars brighter than magnitude 3.00 - 0
Stars within 32 Ly - 0
Messier objects - 1
Meteor showers - None
Bordering
constellations
- Andromeda
- Pisces
- Aries
- Perseus