precession period
61Arthur Thomas Doodson — Dr. Arthur Thomas Doodson (1890 1968) spent much of his life developing the analysis of tidal motions mainly in the oceans but also in lakes, and was the first to devise methods for shallow water as in estuaries. Tide height and current tables… …
62global warming — an increase in the earth s average atmospheric temperature that causes corresponding changes in climate and that may result from the greenhouse effect. [1975 80] * * * Potential increase in global average surface temperatures resulting from… …
63mercury — /merr kyeuh ree/, n., pl. mercuries. 1. Chem. a heavy, silver white, highly toxic metallic element, the only one that is liquid at room temperature; quicksilver: used in barometers, thermometers, pesticides, pharmaceutical preparations,… …
64History of astronomy — History of science …
65Moon — This article is about Earth s Moon. For moons in general, see Natural satellite. For other uses, see Moon (disambiguation) …
66Gregorian calendar — For the calendar of religious holidays and periods, see Liturgical year. For this year s Gregorian calendar, see Common year starting on Saturday. 2011 in other calendars Gregorian calendar 2011 MMXI …
67Full moon cycle — The full moon cycle is a cycle of about 14 lunations over which full moons vary in apparent size and age (time since new moon). The sequence is *Full moon big (perigee at full moon) *Full moon young (perigee at first quarter) *Full moon small… …
68History of science in early cultures — The history of science in early cultures refers to the study of protoscience in ancient history, prior to the development of science in the Middle Ages. In prehistoric times, advice and knowledge was passed from generation to generation in an… …
69Planetary habitability — is the measure of a planet s or a natural satellite s potential to develop and sustain life. As the existence of life beyond Earth is currently uncertain, planetary habitability is largely an extrapolation of conditions on Earth and the… …
70Trepidation (astronomy) — Trepidation as used in the field of astronomy means an imagined oscillation of the equinoxes. It should not be confused with precession. In precession, the equinoxes appear to move slowly through the ecliptic, completing a revolution in… …
