The Winter Triangle is an astronomical asterism formed from three of the brightest stars in the winter sky. It is an imaginary

equilateral triangle In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each oth ...

drawn on the

celestial sphere In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, ...

, with its defining vertices at

Sirius Sirius is the brightest star in the night sky. Its name is derived from the Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated Alpha CMa ...

Betelgeuse Betelgeuse is a red supergiant of spectral type M1-2 and one of the largest stars visible to the naked eye. It is usually the tenth-brightest star in the night sky and, after Rigel, the second-brightest in the constellation of Orio ...

, and Procyon, the primary stars in the three constellations of

Canis Major Canis Major is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin for "greater dog" in contrast t ...

, Orion, and

Canis Minor Canis Minor is a small constellation in the northern celestial hemisphere. In the second century, it was included as an asterism, or pattern, of two stars in Ptolemy's 48 constellations, and it is counted among the 88 modern constellations ...

, respectively.

Visibility

For much of the night in the northern winter, the Winter Triangle is high in the sky at mid-northern

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north po ...

s, but can also be seen during

autumn Autumn, also known as fall in American English and Canadian English, is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, in September (Northern Hemisphere) or March ( S ...

in the early morning to the East. In the

spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a h ...

the winter triangle is visible early in the evening to the West before its stars set below the

horizon The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether ...

. From the southern hemisphere it appears upside down and lower in the sky during the

summer Summer is the hottest of the four temperate seasons, occurring after spring and before autumn. At or centred on the summer solstice, the earliest sunrise and latest sunset occurs, daylight hours are longest and dark hours are shortest, ...

months. The Winter Triangle surrounds most of the faint constellation

Monoceros Monoceros (Greek: Μονόκερως, " unicorn") is a faint constellation on the celestial equator. Its definition is attributed to the 17th-century Dutch cartographer Petrus Plancius. It is bordered by Orion to the west, Gemini to the no ...

, although its brightest stars are of fourth magnitude and hardly noticeable to the naked eye. The triangle includes two first magnitude stars, while Sirius is even brighter. The other bright stars of the winter sky lie around the triangle: Orion including

Rigel Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...

;

Aldebaran Aldebaran (Arabic: “The Follower”, "الدبران") is the brightest star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldeb ...

in Taurus; Castor and Pollux in Gemini; and

Capella Capella is the brightest star in the northern constellation of Auriga. It has the Bayer designation α Aurigae, which is Latinised to Alpha Aurigae and abbreviated Alpha Aur or α Aur. Capella is the sixth-brightest star ...

in Auriga.

The stars of the Winter Triangle

References

{{Reflist, refs= {{cite book, title=A dipper full of stars, author=Lou Williams Page, publisher= Follett Publishing Company, url=https://books.google.com/books?id=uhtPAQAAIAAJ, year=1964, isbn=9995280000 {{cite book, author=Ian Ridpath, author-link=Ian Ridpath, title=The Monthly Sky Guide, url=https://books.google.com/books?id=d4ghAwAAQBAJ&pg=PA15, date=10 December 2012, publisher=

Cambridge University Press Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer. Cambr ...

, isbn=978-1-139-62066-6, pages=15–

External links

Winter Triangle
Night Sky
Deep sky objects inside the Winter TriangleWinter Triangle
at constellation guide

Jim Kaler's stars Asterisms (astronomy)

Visibility

The stars of the Winter Triangle

See also

References

External links