<P> 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 of the equinoxes . A complete precession cycle requires 25,770 years, 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 BC the pole was pointed only five degrees away from Vega . Through precession, the pole will again pass near Vega around AD 14,000 . It is the brightest of the successive northern pole stars . </P> <P> Among the northern Polynesian people, Vega was known as whetu o te tau, the year star . For a period of history it marked the start of their new year when the ground would be prepared for planting . Eventually this function became denoted by the Pleiades . </P> <P> The Assyrians named this pole star Dayan - same, the "Judge of Heaven", while in Akkadian it was Tir - anna, "Life of Heaven". In Babylonian astronomy, Vega may have been one of the stars named Dilgan, "the Messenger of Light". To the ancient Greeks, the constellation Lyra was formed from the harp of Orpheus, with Vega as its handle . For the Roman Empire, the start of autumn was based upon the hour at which Vega set below the horizon . </P> <P> In Chinese mythology, there is a love story of Qi Xi (七夕) in which Niu Lang (牛 郎, Altair) and his two children (β and γ Aquilae) are separated from their mother Zhi Nü (織女, lit . "Weaving Girl", Vega) who is on the far side of the river, the Milky Way . However, one day per year on the seventh day of the seventh month of the Chinese lunisolar calendar, magpies make a bridge so that Niu Lang and Zhi Nü can be together again for a brief encounter . The Japanese Tanabata festival, in which Vega is known as orihime (織姫), is also based on this legend . </P>

Who made precise measurements of the solar system and over 600 stars