Hyperion
3 of the 6 encyclopedias on this shelf carry an entry for Hyperion. All 3 are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
hi-pe'ri-on, in Greek mythology, one of the Titans, son of Uranus (the sky) and Gaea (the earth). He became the father of Helios (the sun), Selene (the moon), and Eos (the dawn). Hyperion was the original sun god and is represented as gloriously bright and beautiful. In astronomy, the name Hyperion is given to one of the satellites of Saturn. Longfellow has given the name Hyperion to a romance which he published in 1839. It is an account of the travels of a young man through foreign countries, and is interspersed with legends, poems, and philosophical discourses.
1000 Classical Characters (1900)
A son of Coelus and Terra, who married Thea. Aurora was their daughter. Keats has written a magnificent poem entitled Hyperion. Hyperion is often used by the poets to signify the sun; as, for instance, by Shakespeare in Titus Andronicus (act v. Sc. 2): "Even from Hyperion's rising in the east, Until his very downfall in the sea." Also in Troilus and Cressida, and other of Shakespeare's plays, the same license is used.
Collier's New Encyclopedia (1921)
in astronomy, the name given to the 7th satellite of Saturn, discovered in 1848, at the Harvard Observatory by G. P. Bond. It is just outside the satellite Titan, and the considerable mass of the latter causes perturbations ions in the orbit of Hyperion, which have proved to be a difficult problem in celestial mechanics, and a unique case in the solar system. (hi-per-met-ro- HYPERMETROPIA pe-a), far-sightedness; it is the opposite of myopia, or near-sightedness, and differs from presbyopia in being congenital.
What Has Changed in the Last Century
The mythology in Aiton's (1910) and 1000 Classical Characters (1900) still reads correctly: Hyperion the Titan, father of Helios, Selene and Eos, and a poetic byword for the sun in Shakespeare and Keats. What has moved is the moon. Collier's called it "a difficult problem in celestial mechanics, and a unique case in the solar system" in 1921, and it turned out to be stranger than that: in 1984 Jack Wisdom, Stanley Peale and François Mignard showed that Hyperion tumbles chaotically, its rotation axis and spin rate never settling, the first body in the solar system known to do so. Voyager 2 in 1981 and the Cassini flybys of 2005 revealed a battered, sponge-like object about 270 km across and so porous that its density is roughly half that of water, and it is no longer the "7th satellite" of a tidy short list — Saturn's confirmed moons now number in the hundreds.
Written for this edition, 2026.