Pleiades

No other object in the night sky has collected names the way the Pleiades has. Hesiod, in the oldest surviving Greek farming poem, tells his reader to begin the harvest when the daughters of Atlas rise before dawn and to plough when they set, and versions of that same habit, using the cluster as the hinge of the working year, recur on every inhabited continent. In Greece they were the Seven Sisters fleeing Orion, who still pursues them across the winter sky.

In India the cluster is Krittika, the six nurses of the war god Karttikeya, and it stood first in the older ordering of the lunar mansions. In Arabia it is Al-Thurayya, the centre of the anwa reckoning by which the rain seasons were counted. In Japan it is Subaru, the gathered ones, a name now carried on a car badge that shows the cluster itself.

Across Polynesia it is Matariki, whose midwinter dawn rising opens the Maori year, an event New Zealand has kept as a public holiday since 2022. The atlas holds several of these readings as entries in their own right, in their own registers, and this entry does not replace them. It is the object they share: a single knot of young stars in the shoulder of Taurus, faint enough that it rewards a dark sky, distinctive enough that no tradition that watched the heavens ever failed to notice it or to hang a season on it.

Most people looking at the Pleiades on a clear night count six stars, yet an odd number of traditions, from Greece to Australia, name seven and then tell a story about the one that is missing. The Greeks said the seventh sister hid in shame or grief, and the lost Pleiad became a commonplace of classical poetry, repeated so widely that astronomers have wondered ever since whether one member of the cluster genuinely faded within human memory. Nothing in the modern record settles it: the cluster contains hundreds of stars, and which ones a sharp eye separates depends on darkness, altitude and the observer. What the eye cannot resolve, the telescope reads plainly. The Pleiades are a true open cluster, a family of young hot blue stars that formed together and are still travelling together, some four hundred light years away, wrapped in faint wisps of dust that photographs show as blue reflection nebulosity.

Charles Messier gave the group the forty fifth place in his catalogue, so the cluster carries the designation Messier 45 alongside all its older names. Its brightest member is Alcyone, which this atlas holds as a star in its own right among the fixed stars of the astrological tradition. The tension between what is seen and what is named, six lights and seven sisters, is part of why the cluster has held human attention for as long as records exist.