Equinox Reference Libraries

Earth Day is a day early each year on which events are held to increase awareness and appreciation of the Earth’s natural environment. It is now coordinated worldwide through the Earth Day Network, founded by Dennis Hayes, and is celebrated in more than 175 countries every year. The United Nations designated April 22 as International Mother Earth Day in 2009, and will continue to be held each...

Autumnal Equinox -- In astronomy, is the equinox at the beginning of autumn in the northern hemisphere: the moment when the sun appears to cross the celestial equator, heading southward. The equinox occurs around September 22-24, varying slightly each year according to the 400 year cycle of leap years in the Gregorian Calendar. In the southern hemisphere, the equinox occurs at the same...

Ecliptic -- The ecliptic is the geometric plane that contains the orbit of the Earth. The orbits of most planets in the Solar System lie very close to it. Seen from the Earth, this is the great circle on the celestial sphere that contains the different positions of the Sun relative to the background stars throughout the year, and most planets can be seen close this circle. The zodiac...