Editing Winter Triangle

{{Short description|Asterism}}
[[File:WinterSky.jpg|thumb|Winter stars with the Winter Triangle front and centre, forming a diamond (actually [[kite (geometry)|kite]]) or [[cross]] with [[Saturn]] above]]
The '''Winter Triangle''' is an astronomical [[asterism (astronomy)|asterism]] formed from three of the brightest stars in the winter sky. It is an imaginary [[isosceles triangle]]{{efn|Procyon-Sirius and Procyon-Betelgeuse are within 0.3° of one another but Sirius-Betelgeuse is significantly longer, so that the largest angle is 78.8°.}} drawn on the [[celestial sphere]], with its defining vertices at [[Sirius]], [[Betelgeuse]], and [[Procyon]], the primary stars in the three constellations of [[Canis Major (constellation)|Canis Major]], [[Orion (constellation)|Orion]], and [[Canis Minor]], respectively.<ref name=ridpath/>

==Visibility==
[[File:Winter Triangle.png|thumb|left|Winter Triangle]]
For much of the night in the northern winter, the Winter Triangle is high in the sky at mid-northern [[latitude]]s, but can also be seen during [[autumn]] in the early morning to the East. In the [[spring (season)|spring]] the winter triangle is visible early in the evening to the West before its stars set below the [[horizon]]. From the [[southern hemisphere]] it appears upside down and lower in the sky during the [[summer]] months.<ref name=dipper/>

The Winter Triangle surrounds most of the faint constellation [[Monoceros (constellation)|Monoceros]], although its brightest stars are of fourth [[apparent magnitude|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]]; [[Aldebaran]] in [[Taurus (constellation)|Taurus]]; [[Castor (star)|Castor]] and [[Pollux (star)|Pollux]] in [[Gemini (constellation)|Gemini]]; and [[Capella]] in [[Auriga (constellation)|Auriga]].

{{clear}}

==The stars of the Winter Triangle==
[[File:Hubble heic0206j.jpg|thumb|right|Winter triangle stars]]
{| class="wikitable"
!Name
!Constellation
![[Apparent magnitude]]
!Luminosity ({{solar luminosity}})
![[Stellar classification|Spectral type]]
!Distance ([[light year|ly]])
|-
![[Sirius]]
|[[Canis Major]]||style="text-align:right"|&minus;1.46||25.4||A1 V||8.6
|-
![[Betelgeuse]]
|[[Orion (constellation)|Orion]]||style="text-align:right"|0.50||90,000 - 150,000||M2 Iab||640
|-
![[Procyon]]
|[[Canis Minor]]||style="text-align:right"|0.34||6.93||F5 IV-V||11.5
|}

==See also==
* Spring [[Great Diamond]]
* [[Summer Triangle]]
* [[Winter Hexagon]]
* [[Northern Cross (asterism)|Northern Cross]]

==Notes==
{{notelist}}

==References==
{{Reflist|refs=

<ref name=dipper>{{cite book|title=A dipper full of stars|author=Lou Williams Page|publisher=[[Follett Corporation|Follett Publishing Company]]|url=https://books.google.com/books?id=uhtPAQAAIAAJ|year=1964|isbn=9995280000}}</ref>

<ref name=ridpath>{{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]]|isbn=978-1-139-62066-6|pages=15–}}</ref>

}}

==External links==
*[http://www.souledout.org/nightsky/wintertriangle/wintertriangle.html Winter Triangle] Night Sky
*[http://www.derekscope.co.uk/2014/02/deep-sky-objects-inside-winter-triangle/ Deep sky objects inside the Winter Triangle]
*[http://stars.astro.illinois.edu/sow/wintri-p.html Winter Triangle] Jim Kaler's stars

[[Category:Asterisms (astronomy)]]