Editing Vega (section)

==Observation==
[[Image:Summer triangle.png|left|thumb|upright=1.2|The [[Summer Triangle]]]]

Vega can often be seen near the [[zenith]] in the mid-northern [[latitude]]s during the evening in the [[Northern Hemisphere]] summer.<ref name=pasachoff2000/> From mid-southern latitudes, it can be seen low above the northern horizon during the [[Southern Hemisphere]] winter. With a [[declination]] of +38.78°, Vega can only be viewed at latitudes north of [[51st parallel south|51° S]]. Therefore, it does not rise at all anywhere in [[Antarctica]] or in the southernmost part of South America, including [[Punta Arenas]], [[Chile]] (53° S). At latitudes to the north of [[51st parallel north|51° N]], Vega remains continuously above the horizon as a [[circumpolar star]]. Around July 1, Vega reaches midnight [[culmination]] when it crosses the [[Meridian (astronomy)|meridian]] at that time.<ref name=burnham1978/> Complementarily, Vega swoops down and kisses the horizon at true North at midnight on Dec 31/Jan 1, as seen from 51° N. [[File:Path of Vega at winter solstice.png|thumb|Path of Vega at winter solstice, as seen from 51°N ]]

[[File:Precession N.gif|thumb|The path of the north celestial pole among the stars due to the precession. Vega is the bright star near the bottom.|alt=Small white disks representing the northern stars on a black background, overlaid by a circle showing the position of the north pole over time]]
Each night the positions of the stars appear to change as the Earth rotates. However, when a star is located along the Earth's axis of rotation, it will remain in the same position and thus is called a [[pole star]]. The direction of the Earth's axis of rotation gradually changes over time in a process known as the [[Precession (astronomy)|precession of the equinoxes]]. A complete precession cycle requires 25,770&nbsp;years,<ref name=chaikin1990/> during which time the pole of the Earth's rotation follows a circular path across the [[celestial sphere]] that passes near several prominent stars. At present the pole star is [[Polaris]], but around 12,000 BCE the pole was pointed only five degrees away from Vega. Through precession, the pole will again pass near Vega around 14,000 CE.<ref name=roy_clarke2003/> Vega is the brightest of the successive northern pole stars.<ref name="allen1963"/> In 210,000 years, Vega will become [[historical brightest stars|the brightest star]] in the night sky,<ref name=tomkin1998/> and will peak in brightness in 290,000 years with an apparent magnitude of –0.81.<ref name=tomkin1998/>

This star lies at a [[Vertex (geometry)|vertex]] of a widely spaced [[Asterism (astronomy)|asterism]] called the [[Summer Triangle]], which consists of Vega plus the two first-magnitude stars [[Altair]], in [[Aquila (constellation)|Aquila]], and [[Deneb]] in [[Cygnus (constellation)|Cygnus]].<ref name=pasachoff2000/> This formation is the approximate shape of a [[right triangle]], with Vega located at its [[right angle]]. The Summer Triangle is recognizable in the northern skies for there are few other bright stars in its vicinity.<ref name=upgren1998/>