List of stars in Triangulum
|Right ascension||2 h|
|Area||132 sq. deg. (78th)|
|Stars with planets||1|
|Stars brighter than 3.00m||0|
|Stars within 10.00 pc (32.62 ly)||0|
|Brightest star||β Tri (3.00m)|
|Nearest star||δ Tri
(35.29 ly, 10.82 pc)
Triangulum is a small constellation in the northern sky. Its name is Latin for triangle, which distinguishes it from Triangulum Australe in the southern sky. Its name derives from its three brightest stars, of third and fourth magnitude, which form a nearly isosceles long and narrow triangle. Triangulum was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations.
Notable features 
Triangulum has three stars of the first magnitude. Its brightest star is the white giant star β Trianguli (3.00m) with a close, dimmer companion. Its second-brightest star, the yellow-white subgiant star α Trianguli (3.41m) with a close dimmer companion, is also known as Caput Trianguli, and is at the apex of the triangle. 6 Trianguli, (known in some older sources as ι), is an "attractive double star with a noticeable color contrast" that can be split by medium-sized telescopes into a strong yellow and a pale blue star. Both components are themselves close binaries.
Deep-sky objects 
The Triangulum Galaxy, also known as Messier 33, was discovered by Giovanni Battista Hodierna in the 1600s. A distant member of the Local Group, it is about 2.3 million light years away, and at magnitude 5.8, it is bright enough to be seen by the naked eye under the darkest skies. Under light-polluted skies, it is challenging or invisible even in a small telescope or binoculars. Because of its low surface brightness, low power is required. It has a diameter of 46,000 light-years and is thus smaller than both the Andromeda Galaxy and the Milky Way. Recent measurements of its motion indicate that it is moving at 190 kilometres (120 mi) per second in the direction of the Andromeda Galaxy, which has led astronomers to surmise that it may actually be orbiting the larger galaxy.
In addition to M33, there are several NGC galaxies, all with magnitudes fainter than 11. The largest of these include the 10 arcminute long magnitude 12 NGC 925 spiral galaxy and the 5 arcminute long magnitude 11.6 NGC 672 barred spiral galaxy.
History and mythology 
In the Babylonian star catalogues, Triangulum together with γ And formed the constellation known as MULAPIN (𒀯𒀳) "The Plough". It is notable as the first constellation listed in the pair of tablets containing the canonical star lists compiled around 1000 BC, which are thus known as the MUL.APIN by their incipit. The Plough was the first constellation of the "Way of Enlil", i.e. northernmost quarter of the Sun's path, corresponding to the 45 days on either side of summer solstice.
The Greeks called Triangulum Δελτωτόν, as the constellation resembled an upper-case Greek letter delta (Δ) to the earlier Greeks. It was transliterated into Deltoton by Roman writers. Later, it became the Latin Deltotum. Greek astronomers called it as Τρίγωον. And later, it became Trigonum. Originally, it represented an equilateral triangle, but is now depicted as a scalene triangle.
In non-Western astronomy 
In Chinese astronomy, the stars of Triangulum along with several in Andromeda were incorporated into T'ien-ta-tsiang-kiun (the "Great Celestial General"), the fifth paranatellon of the second house of the White Tiger of the West. Gamma Trianguli represented the General itself, while 14 Trianguli and Upsilon Andromedae represented his standard-bearers. The rest of the stars in Triangulum represented other officers.
See also 
- Robert Burnham, Jr (1978). Burnham's Celestial Handbook, Dover Publications, New York. ISBN 0-486-24065-7
- Wilkins, Jamie; Dunn, Robert (2006). 300 Astronomical Objects: A Visual Reference to the Universe. Buffalo, New York: Firefly Books. ISBN 978-1-55407-175-3.
- John H. Rogers, "Origins of the ancient contellations: I. The Mesopotamian traditions", Journal of the British Astronomical Association 108 (1998) 9–28
- Staal 1988, pp. 48-49
- Allen, R. H., (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 415. ISBN 0-486-21079-0.
- Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0-00-725120-9. Princeton University Press, Princeton. ISBN 978-0-691-13556-4.
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