![]() Early July marks the point of aphelion, or furthest distance, from the sun. In early January, it is at its perihelion, or closest distance to the sun. The word "equinox" itself comes from the Latin equi, meaning "equal", and nox, or "night".īecause the earth orbits the sun in an elliptical pattern, its distance from the sun varies at different times of the year. This happens twice in each calendar year: once in late March and again in late September. With the solar terminator (also known as the "edge" between night and day) falling perpendicular to the equator, Earth's northern and southern hemispheres are equally illuminated, and the length of day and night are approximately equal all over the world. It is the point where the ecliptic pathway of the sun intersects with the celestial equator, an imaginary plane representing a projection of the earth's equator out into space. ![]() Because seasons in the Southern Hemisphere are the opposite of those in the north, the southern vernal equinox occurs on September 22 or 23, and lasts until their summer solstice in December.Īn equinox occurs when the center of the sun is directly above the earth's equator, travelling along the earth's equatorial line. Known as the "Spring-" or "March-" equinox it is widely considered to be the beginning of the spring season, which lasts until the summer solstice in late June. In the Northern Hemisphere, the vernal equinox occurs at a point falling between March 19 and 21, usually on March 20. Editorial credit: Harjeet Singh Narang / They smoke this sacred tobacco in a ceremony marking the return of longer days.Īnd at Stonehenge's equinox celebrations in England, druids, pagans, and anyone else who wants to join in gather to witness the sunrise over the ancient stones.What is the Vernal Equinox? Celebration of Holi in Nandgaon, India. The Lakota connect the earth with the sky by making tobacco from the red willow tree, which matches the Dried Willow constellation, where the sun rises on the spring equinox. Some cultures continue to celebrate the equinox today, like the Lakota Tribe of the U.S. ( Listen: In this episode of our podcast Overheard, we chat about Nowruz, an ancient Persian holiday marking the new year at the moment of the vernal equinox. From constructed monuments, like pyramids, to stone engravings that acted as calendars, to churches that incorporated the sun into their architecture, civilizations marked the passing of the sun and the seasons with great accuracy. Photograph by HUGO BORGES, AFP/Getty Images Marking the equinoxĪncient cultures have tracked the equinoxes in different ways over the millennia. Right: View of the sun behind the Temple of the Seven Dolls in the Mayan archaeological site of Dzibilchaltun, in Merida, Yucatan state, Mexico, on March 21, 2021, during the spring equinox. As on Earth, equinoxes occur every half-year on Saturn, but that equals 15 years on Earth, making Cassini's photo session a unique event. In 2009, the Cassini probe in orbit around Saturn captured an equinox on the ringed planet. That means one half of the planet is still a little more lit than the other, even on an equinox.Įarth isn’t the only planet that experiences equinoxes: Every planet in our solar system has them. The terminator doesn’t perfectly divide the planet into dark and light Earth’s atmosphere bends sunlight by 37 miles (60 kilometers), which equals half a degree. ![]() Two times a year, Earth’s orbit and its axial tilt combine so that the sun sits right above Earth’s Equator, casting the dividing line between the light and dark parts of the planet- the so-called terminator, or twilight zone-through the North and South Poles. Our planet normally orbits the sun on an axis that’s tilted 23.5 degrees, meaning that the hemispheres trade off getting more warmth from the sun. What are equinoxes? What causes these astronomical events? Find out how they influence the seasons and hours of daylight on each planet.
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