Equinoxes | National Geographic

twice a year day and night fall into

balance lasting for nearly equal lengths

known as equinoxes flattened for equal

night they occur in March and September

and along with solstices marked the

changing of seasons as earth travels

around the Sun astronomers like to

describe the equinoxes within the

conceptual celestial sphere here the

heavens are projected around the earth

like an enormous planetarium the model

is bisected by the celestial equator a

projection of Earth's own equator the

equinox occurs at the point at which the

sun's path or ecliptic crosses the

celestial equator in spring it is known

as the vernal equinox and in fall the

autumnal equinox the other two seasonal

points on the sun's path are the two

solstices in the northern hemisphere the

summer solstice marks the longest day of

the year while the winter solstice marks

the shortest the seasonal aligning of

the Sun has been more than just a unique

celestial event for humankind throughout

history ancient sites like Stonehenge in

England and Machu Picchu in Peru have

well-documented solar alignments during

the solstices

similarly the equinoxes have been

associated with some amazing man-made

phenomenon in the ancient Maya city of

Chichen itzá the Great Pyramid known as

El Castillo is oriented along Cardinal


during the equinoxes shadows cast by the

railings create the illusion of a

writhing serpent body descending the

northern steps where it joins the carved

serpents head at the base of the

stairway the cultural significance of

the fall equinox and changing of seasons

continues today especially in the

northern hemisphere where the autumnal

equinox occurs around harvest season in

fact the full moon nearest the autumnal

equinox is commonly referred to as the

Harvest Moon in China and other Asian

countries this time is celebrated with

the mid-autumn kn'l festival the origins

are linked to the birth of the moon

goddess and festival traditions revolve

around families with reunions and feasts

and special moon cakes in Jewish culture

thanks for the harvest is given during

the week-long Feast of the Tabernacles

or Sukkot families eat meals and

temporary shelters outside recalling the

Israelites days in the wilderness after

the exodus from Egypt