mean vernal equinox

См. также в других словарях:

• equinox — i. One of the two points of intersection of the ecliptic and the celestial equators, occupied by the sun when its declination is 0°. Also called an equinoctial point. That point occupied on or about March 21, when the sun’s declination changes… …   Aviation dictionary

• Equinox — This article is about the astronomical event when the sun is at zenith over the Equator. For other uses, see Equinox (disambiguation). For the same event happening on other planets and setting up a celestial coordinate system, see Equinox… …   Wikipedia

• mean sun — noun a theoretical sun that moves along the celestial equator at a constant speed and completes its annual course in the same amount of time the real sun takes at variable speeds • Hypernyms: ↑model, ↑theoretical account, ↑framework * * * noun… …   Useful english dictionary

• Equinox (celestial coordinates) — In astronomy, equinox is a moment in time at which the vernal point, celestial equator, and other such elements are taken to be used in the definition of a celestial coordinate system. The position at other equinoxes can be computed by taking… …   Wikipedia

• Gregorian 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 …   Wikipedia

• CALENDAR — (Heb. לוּחַ, lu aḥ). The present Jewish calendar is lunisolar, the months being reckoned according to the moon and the years according to the sun. A month is the period of time between one conjunction of the moon with the sun and the next. The… …   Encyclopedia of Judaism

• Earth — This article is about the planet. For other uses, see Earth (disambiguation). Earth   …   Wikipedia

• Earth's rotation — is the rotation of the solid Earth around its own axis. The Earth rotates towards the east, which can be observed by orientation with a magnetic compass at sunrise. As viewed from the star Polaris, the Earth turns counter clockwise. Rotation… …   Wikipedia

• Rotation period — The rotation period of an astronomical object is the time it takes to complete one revolution around its axis of rotation relative to the background stars. It differs from the planet s solar day, which includes an extra fractional rotation needed …   Wikipedia

• calendar — calendrical /keuh len dri keuhl/, calendric, calendarial /kal euhn dair ee euhl/, calendarian, calendaric, adj. /kal euhn deuhr/, n. 1. a table or register with the days of each month and week in a year: He marked the date on his calendar. 2. any …   Universalium

• Tropical year — A tropical year (also known as a solar year), for general purposes, is the length of time that the Sun takes to return to the same position in the cycle of seasons, as seen from Earth; for example, the time from vernal equinox to vernal equinox,… …   Wikipedia