By the processional movement, the position of the sun in the ecliptic at an equinox or solstice sweeps round the ecliptic in about 25,000 years. Now if we suppose twelve ecliptic constellations of equal size--that is, 30° long (30° × 12 = 360°)--the time it would take the sun's place at the vernal equinox to pass through one constellation would be (25000∕12 =) 2083 years. If the constellation of the Bull were twice as long formerly as it is now (when the constellations are twice as numerous), of course this period would be doubled. So that the statement that the sun at the equinox was in the Bull does not help us very much to an actual date, and the constellation of the Lion could have been established 2000 years after the Bull, and yet have marked the summer solstice. Further, if all the stars of the Bull (speaking generally) are seen at dawn--that is, before the sun rises--the sun has not yet reached the Bull. We can then, at all events, fix a minimum of time. The sun's longitude at the vernal equinox being always 0, the longitude of the most easterly part of the constellation, assuming this part not to have been changed, will give us the number of years that have elapsed. I now go on to state Jensen's view as to the date of the introduction of the god Marduk into Babylonian mythology, or, in other words, of the worship of the spring-tide sun. Jensen remarks:-- "It may safely be assumed that the constellations of the Scorpion and the Bull actually originated at the latest at a time when the autumnal and vernal equinoctial points respectively coincided with their principal stars. But this was the case more than 4900 years ago. But if we assume that Taurus and Scorpio were given their names at a time when their main stars rose before the sun at the time of the vernal and autumnal equinoxes respectively, we should obtain as the date of the establishment of the constellations of Taurus and Scorpio in the skies about the year-5000.[179] According to Dr. Tetens, the sun stood at the tips of the horns of the Bull at the commencement of spring 6000 years ago. At this time, therefore, Taurus had completely risen above the eastern horizon at sunrise.