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physical phenomena > event > celestial event > periodic celestial event

periodic celestial event
subject			fact

periodic celestial event	has period
	has definition Celestial event which occurs with a very regular period
	is a kind of celestial event
event	has duration
	has synonym world point
	has time of occurrence

Kinds of periodic celestial event :

• active Sun (4 facts) - The Sun during its 11-year cycle of activity when spots, flares, prominences, and variations in radiofrequency radiation are at a maximum.
• equinox (2 kinds, 13 facts) - One of two points in the sky that represent where the Sun appears to cross the plane of the Earth's equator. From the Earth's viewpoint therefore, the Sun reaches one point at a quarter, the other at three quarters of the way through the sidereal year: the vernal (spring) equinox is thus on or around 21 March, the autumnal on or around 22 September. The actual points in the sky change slightly every year through a process called precession., Either of the two points on the celestial sphere where the celestial equator intersects the ecliptic., Either of the two points on the celestial sphere at which the ecliptic intersects the celestial equator; also the time at which the Sun passes through either of these intersection points; i.e., when the apparent longitude (see apparent place; celestial longitude) of the Sun is 0° or 180°. (See catalog equinox; dynamical equinox for precise usage.)
• Forbush decrease (6 facts) - A decrease in cosmic-ray intensity during active Sun.
• location dependent periodic celestial event (8 kinds, 28 facts) - Periodic celestial event which depends on the observers location on the planet
• meteor shower (12 kinds, 60 facts) - A profusion of meteors that fall within a period of a few hours and that appear to radiate from a common point in the sky. Shower meteors are usually low-density material and have high eccentricities., temporary increase in the rate at which meteors are observed when the target runs into a swarm of meteoroids that share a common orbit
• orbital event (20 kinds, 58 facts) - Periodic celestial event in the orbit of a celestial body
• solar cycle (4 facts) - The 11-year period between maxima (or minima) of solar activity. Every 11 years the magnetic field of the Sun reverses polarity; hence the more basic period may be 22 years.
• solstice (2 kinds, 5 facts) - One of the two points on the ecliptic at which the Sun appears to be farthest away from the celestial equator (representing therefore mid-summer or mid-winter).