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Equinoxes and Solstices
An equinox occurs twice a year (around 20 March and 22 September), when the plane of the Earth's equator passes the centre of the Sun.
A solstice occurs twice a year (around 21 June and 21 December), when the Sun reaches its highest or lowest excursion relative to the celestial equator on the celestial sphere.
Geocentric conjunction in right ascension
When two planets or a planet and the moon are aligned in right ascension :
Inferior conjunction
When earth, an inner planet and the sun are aligned (same side of sun) :
Superior conjunction
When earth, an inner planet and the sun are aligned (opposite side of sun) :
Quadrature west
When angle between earth, sun and an outer planet is a right angle (with planet in the west direction for northern hemisphere) :
Quadrature east
When angle between earth, sun and an outer planet is a right angle (with planet in the east direction for northern hemisphere) :
Opposition
When an outer planet, earth and sun are aligned :
Entry in a new Constellation
When sun, moon or a planet enters in a new constellation :
Meteor Shower
Start, peak and end of Meteor Showers.
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