linguistic:voice_change, structural:reformatting, stylistic:style_transfer
Astronomical role of M45 in antiquity

The M45 group played an important role in ancient times for the establishment of many calendars thanks to the combination of two remarkable elements. The first, which is still valid, is its unique and perfectly identifiable aspect on the celestial vault near the ecliptic. The second, essential for the ancients, is that in the middle of the third millennium BC, this asterism (a prominent pattern or group of stars that is smaller than a constellation) marked the vernal point.

The importance of this asterism is also evident in northern Europe. The Pleiades cluster is displayed on the Nebra sky disc that was found in Germany and is dated to around 1600 BC. On the disk the cluster is represented in a high position between the Sun and the Moon.

This asterism also marks the beginning of several ancient calendars:

Although M45 is no longer at the vernal point, the asterism still remains important, both functionally and symbolically. In addition to the changes in the calendars based on the lunar stations among the Indians and the Arabs, consider the case of an ancient Yemeni calendar in which the months are designated according to an astronomical criterion that caused it to be named Calendar of the Pleiades: the month of ḫams, literally "five", is that during which the Sun and al-Ṯurayyā, i.e. the Pleiades, deviate from each other by five movements of the Moon, i.e. five times the path that the "Moon" travels on average in one day and one night, to use the terminology of Abd al-Rahman al-Sufi.