Pleiades
2 of the 6 encyclopedias on this shelf carry an entry for Pleiades. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
ple'ya-dez, in Greek mythology, a bevy of nymphs, daughters of Atlas, belonging to the train of the huntress-goddess Artemis (Diana). They were pursued by the giant Orion. In terror they applied for protection to Zeus, who changed them to doves and placed them as a constellation in the sky. There were originally seven of them, but one has disappeared. The story runs that one of the nymphs, Electra, left her place that she might not behold the destruction of Troy, which city was founded by her son, Dardanus. The other stars of the group have been paler since they looked on the awful sight of that city's ruin. The lost Pleiad is alluded to frequently by the poets. The name La Pleiade or the Pleiad is given in literature to several different groups of seven poets living at the same time. One such group is of ancient poets, including Theocritus, Callimachus, and Homer; another is of French poets of the sixteenth century. Many a night I saw the Pleiades, rising through the mellow shade Glitter like a swarm of fireflies, tangled in a silver braid.
Collier's New Encyclopedia (1921)
or PLEIADS, a group of stars in the constellation Taurus, the Bull. The stars are so close together that it is a difficult to say how many are seen by the naked eye. According to mythology, the Pleiades were the seven daughters of Atlas, who, being pursued by Orion, were changed by Jupiter into doves. They were afterward translated to the heavens, where they formed the assemblage of the Seven Stars in the neck of Taurus.
What Has Changed in the Last Century
The myth as Aiton's told it in 1910 is still told the same way, and the "lost Pleiad" is still what most people notice — six stars easily visible where tradition counts seven. What has changed is the astronomy: Collier's in 1921 could only say the stars are "so close together that it is difficult to say how many are seen by the naked eye," whereas the Pleiades are now known to be a genuine physical open cluster of well over a thousand stars, about 100 million years old, moving together through space. Its distance was settled only recently, after the Hipparcos satellite's 1997 figure of roughly 390 light years clashed with other methods; radio interferometry and the Gaia mission put it near 444 light years. The blue haze around the brightest stars, once assumed to be gas left from their birth, is now understood as an unrelated dust cloud the cluster happens to be drifting through.
Written for this edition, 2026.