Zodiac
2 of the 6 encyclopedias on this shelf carry an entry for Zodiac. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
in astronomy. The zone o broad belt of constellation which the sun traverses during the year in passing around the ecliptic . The moon and major planets also move within the same area. The breadth of the zodiac is about eight and a half degrees on each side of the ecliptic, or 17 in all. It is inclined to the equinoctial at an angle of 23°28′, the points of intersection being reached by the sun, one at the vernal and the other at the autumnal equinox. The great circle of the zodiac was divided by the ancients into 12 equal portions called signs. They were named from the constellations then adjacent to them in the following order: Aries, the Ram; Taurus, the Bull; Gemini , the Twins; Cancer, the Crab; Leo, the Lion; Virgo , the Virgin; Libra, the the Scorpion; Sagittarius, the Archer; Capricornus, the Goat; Aquarius, the Waterbearer; and Pisces, the Fishes. The sun formerly entered Aries on March 20; now, owing to the precession of the equinoxes, the point of the heavens intersected by the celestial equator and the ecliptic, technically called the first point of Aries, has moved well into Pisces. rly glow the Balance; Scorpio,
Aiton's Encyclopedia (1910)
zo'di-ak, a belt 16 deg. wide, 8 deg. on each side of the ecliptic. The Germans call it the animal circle, Thierkreis. The space of the zodiac is divided into twelve areas, groups, or constellations, forming a continuous belt of stars extending entirely around the heavens. In the spring the sun passes through the constellations of Aries, or the ram; Taurus, the bull; Gemini, the twins. In summer his companions day and night are first Cancer, the crab; then Leo, the lion; then Virgo, the virgin. In autumn the sun is in Libra, the scales; Scorpio, the scorpion; and Sagittarius, the archer. In winter he travels through Capricornus, the goat; Aquarius, the waterman; and Pisces, the fishes, back to his starting place in the ram again. The constellation of the zodiac which is on the eastern horizon at midnight in January is in mid-sky at the hour of midnight in April and in the western horizon at the hour of midnight in July. See Astrology ; Constellation
What Has Changed in the Last Century
The geometry set out by Aiton's in 1910 and Collier's in 1921 is still correct: the ecliptic is tilted about 23.5 degrees to the celestial equator, the sun's yearly path runs through the same twelve named signs, and precession has indeed carried the "first point of Aries" back into Pisces, as Collier's noted. What has changed is the bookkeeping. When the International Astronomical Union fixed the boundaries of the 88 constellations in 1928 (published 1930), the ecliptic was seen to cross a thirteenth, Ophiuchus, between Scorpius and Sagittarius, a point that resurfaces in the press every few years as the "missing sign." The constellations are now firmly astronomical labels only; Aiton's cross-reference to "See Astrology" would not appear in a modern astronomy article, since astrology's signs are fixed 30-degree divisions no longer aligned with the star groups that named them.
Written for this edition, 2026.