How did pleiades get is name?

Answer 1

Names

Several of the most prominent male Olympian gods (including Zeus, Poseidon, and Ares) engaged in affairs with the seven heavenly sisters.

Here are the seven names from Classical Greece. Their mother was Pleione.

These relationships resulted in the birth of their children, the seven daughter -nymphs.

Maia, eldest of the seven Pleiades, was mother of Hermes by Zeus.

Electra, mother of Dardanus and Iasion, by Zeus.

Taygete, mother of Lacedaemon, also by Zeus.

Alcyone, mother of Hyrieus, Hyperenor and Aethusa; Hyperes and Anthas] and Epopeus by Poseidon.

Celaeno, mother of Lycus and Nycteus by Poseidon; and of Eurypylus and Euphemus also by Poseidon.

Sterope, also Asterope, mother of King Oenomaus of Elis by Ares or wife of Oenomaus instead.

Merope, youngest of the Pleiades. In other mythic contexts, she married Sisyphus and, becoming mortal, faded away. Merope bore Sisyphus several sons including Glaucus.

Answer 2

The Pleiades is named after the seven sisters of Greek mythology, the daughters of Atlas (one of the titans) because it was charted that it consisted of seven stars, though of course it only appeared this way before they could be resolved into the thousands that actually make up the cluster. The cluster is also called 'The Seven Sisters' for similar reasons.