CELESTIAL SOUTH POLE. Point on the celestial sphere, visible from any location in the southern hemisphere where the relevant part of the sky is unobscured, around which the celestial bodies appear to rotate daily (in a clockwise direction).
*CELESTIAL SPHERE. Imaginary sphere surrounding the observer on which the celestial bodies can be considered to be positioned.
*CIRCUMPOLAR STAR. For a given location on earth, a star that is always above the horizon and so never sets or rises.
CODEX. In the Mesoamerican context, an indigenous “book” made from pages of painted tree bark folded together in concertina fashion.
CODICES. Plural of Codex.
COSMOGRAM. A symbolic representation of the cosmos, as found in some Mesoamerican codices.
CULMINATION. The moment when a celestial object reaches its highest altitude, which happens when it crosses the meridian.
*DECLINATION. “Latitude” on the spinning celestial sphere.
*DIURNAL MOTION. Daily rotation of the celestial sphere.
DOLMEN. Most usually, a megalithic monument comprising a large horizontal stone supported by a number of upright stones. Sometimes the term is applied to a wider range of megalithic tombs.
*ECLIPTIC. The annual path of the sun through the stars on the celestrial sphere.
*ELEVATION. Height above sea level. Cf. Altitude.
*EQUINOXES. Technically, the times when the sun’s declination is zero, but often loosely taken to mean the halfway point in time between the solstices.
*EXTINCTION. The dimming of a star at low altitude due to the earth’s atmosphere.
GNOMON. A rod, pole, or equivalent device whose function is to cast a shadow for the purposes of reckoning time, typically as part of a sundial.
*HELIACAL RISE. The annual first appearance of a star, or the first appearance of a planet, in the eastern sky before sunrise after a period of invisibility.
*HELIACAL SET. The annual last appearance of a star, or the last appearance of a planet, in the western sky after sunset before a period of invisibility.
HENGE. A prehistoric enclosure consisting of a circular ditch and adjacent external bank, of which many were constructed in Britain and Ireland during the Late Neolithic period. Associated rings of timber posts or stone circles were common but not universal, and were not always part of the original design. Although the term “henge” derives from Stonehenge (that is, like Stonehenge but without the stones), Stonehenge itself—ironically—is not now generally considered a henge, since the circular ditch and bank at the site are of early (Middle Neolithic) date and the bank is internal to the ditch.
HIEROPHANY. An appearance of the sacred, or the experience of this. The term is commonly used to describe a spectacular effect perceived as mystical, such as those produced by sunlight and shadow at ancient sites, but only on rare occasions.
INFERIOR PLANET. A planet whose orbit is closer to the sun than the Earth’s. The two inferior planets, Venus and Mercury, are both visible to the naked eye, although Mercury, being closer to the sun, is more seldom seen. Cf. Inner planet and Superior planet.
INNER PLANET. One of the four planets closest to the sun, namely Mercury, Venus, Earth and Mars. Cf. Inferior planet and Outer planet.
KIVA. A subterranean building in the southwestern United States, roofed and used as a meeting place or for sacred ceremonies.
LATITUDE. Angular distance from the equator of a location on the earth. Because of a confusion of terminology it is better to speak of declination on the spinning celestial sphere.
LUNATION. The time that it takes the moon to complete its cycle of phases. Equivalent to synodic month.
MAJOR STANDSTILL LIMITS. The most northerly or southerly possible rising or setting positions of the moon, which can only be reached around the time of a “major standstill,” which only occurs every 18.6 years. See the encyclopedia entry Moon, Motions of.
MEGALITHIC MONUMENT. Any monument built of large stones, applied particularly to prehistoric tombs and temples built in Europe during the Neolithic and Early Bronze Age.
*MERIDIAN. Imaginary line across the sky, joining the north point on the horizon to the south point and passing through the zenith.
MIDSUMMER SUNRISE. Popular term for sunrise at the summer solstice.
MIDSUMMER SUNSET. Popular term for sunset at the summer solstice.
MIDWINTER SUNRISE. Popular term for sunrise at the winter solstice.
MIDWINTER SUNSET. Popular term for sunset at the winter solstice.
NADIR. The point directly beneath the observer, also known as the antizenith. Cf. Zenith.
NEOLITHIC. Broadly speaking, a prehistoric society whose subsistence is based on animal herding or agriculture but lacks any knowledge of metallurgy. Meaning “New Stone Age,” the term is a remnant of the “three-age” classification (Stone Age, Bronze Age, Iron Age) that has long been superseded as a primary indicator of social development but is often still retained for convenience. The term is seldom used in reference to the Americas.
*OBLIQUITY OF THE ECLIPTIC. The amount by which the earth’s axis is “tilted” with respect to the plane of its orbit about the sun. More precisely, the angle between the earth’s axis and the direction perpendicular to the plane of its orbit.
OUTER PLANET. One of the five planets furthest from the sun, namely Jupiter, Saturn, Uranus, Neptune and Pluto. Only Jupiter and Saturn are visible to the naked eye. Cf. Inner planet and Superior planet.
*PARALLAX. The difference between the position of an object in the sky as viewed (conceptually) from the center of the earth and (actually) from somewhere on the earth’s surface. It is only significant in the case of the moon.
*PRECESSION. Short for “precession of the equinoxes.” A gradual change in the orientation of the earth’s axis with respect to distant space, which results in the positions where the solstices and equinoxes occur slowly shifting along the earth’s orbit. This significantly alters the position of any given star in the sky over a timescale of centuries.
*PRECISION. The degree of consistency of several measurements of the same thing by a particular method. Cf. Accuracy.
QUADRANT. An instrument for measuring the altitude of a celestial body.
QUADRIPARTITE COSMOLOGY. A perception of the world, or cosmos, as viewed from a central place as being divided horizontally into four quarters, each with distinctive properties and qualities.
*REFRACTION. The bending of light, in particular as it passes through the atmosphere, which causes astronomical objects near to the horizon to appear higher than they actually are.
SARSEN. A type of large sandstone block found extensively in southern England and used in the construction of Stonehenge.
*SOLSTICES. The times of year when the sun reaches its highest or lowest declination and moves on its most extreme daily path across the sky (which, outside the tropics, is its highest or lowest). One solstice occurs on or close to June 21 and the other on or close to December 22.