Editing Thuban (section)

=== Pole star ===
[[File:Precession N.gif|thumb|left|Precession of the equinoxes for the Pole Star. Thuban is toward the right of the image, below the −2000 mark.]]
Due to the [[Precession (astronomy)|precession]] of [[Earth]]'s rotational axis, Thuban was the naked-eye star closest to the [[north pole]] from 3942&nbsp;BC, when it superseded [[Tau Herculis]] as the pole star, until 1793&nbsp;BC, when it was superseded by [[Kappa Draconis]]. It was closest to the pole in 2830&nbsp;BC, when it was less than 10&nbsp;[[arcminutes]] away from the pole.<ref name="MOORE">{{Cite book |doi=10.1007/978-1-4471-3613-2 |title=The Observer's Year |year=1998 |last1=Moore |first1=Patrick |isbn=978-3-540-76147-1 |url-access=registration |url=https://archive.org/details/observersyear36600moor}}</ref> It remained within one degree of celestial north for nearly 200 years afterwards, and even 900 years after its closest approach, was just 5° off the pole. Thuban was considered the pole star until about 1800&nbsp;BC, when the much brighter [[Beta Ursae Minoris]] (Kochab) began to approach the pole as well.

Having gradually drifted away from the pole over the last 4800 years, Thuban is now seen in the night sky at a [[declination]] of {{DEC|64|20|45.6}}, [[Right ascension|RA]] {{RA|14|04|33.58}}. After moving nearly 47° off the pole by [[List of future astronomical events#After 10,000 AD|10,000&nbsp;AD]], Thuban will gradually move back toward the north celestial pole. In [[List of future astronomical events#After 10,000 AD|20,346&nbsp;AD]], it will again be the pole star, that year reaching a maximum declination of {{DEC|88|43|17.3}}, at right ascension {{RA|19|08|54.17}}.{{citation needed|date=July 2015}}

{| class="wikitable" style="margin: 1em auto 1em auto; text-align:center;"
! Preceded by
! [[Pole star]]
! Succeeded by
|-
| [[Tau Herculis]]
| c. 3900–1800 BC
| [[Kochab]]
|}