How do equinoxes occur

News Headlines. Customize Your Weather. Privacy Policy. The Seasons, the Equinox, and the Solstices Weather. Current Hazards. Rivers and Lakes. Climate and Past Weather. The Seasons We all know that the Earth makes a complete revolution around the sun once every days, following an orbit that is elliptical in shape.

The Relationship Between Length of Day and Temperature There is a lag between the longest day of the year and the warmest average temperatures for most mid and high latitude locations. Current Weather. Forecast Maps. Hour by Hour Forecast. Winter Weather. Graphical Hazards. And 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.

All rights reserved. What is an Equinox? What are equinoxes? What causes these astronomical events? Find out how they influence the seasons and hours of daylight on each planet. Why do equinoxes happen? Share Tweet Email. Read This Next Wild parakeets have taken a liking to London. Animals Wild Cities Wild parakeets have taken a liking to London Love them or hate them, there's no denying their growing numbers have added an explosion of color to the city's streets.

India bets its energy future on solar—in ways both small and big. Environment Planet Possible India bets its energy future on solar—in ways both small and big Grassroots efforts are bringing solar panels to rural villages without electricity, while massive solar arrays are being built across the country.

Epic floods leave South Sudanese to face disease and starvation. Equilux "equal light" , on the other hand, is the term for when day and night are exactly equal. And, because of how sunrise and sunset are defined, the equilix occurs a few days before the spring equinox and a few days after the autumn equinox, according to the U.

Equinoxes don't necessarily occur on the same day each year, rather they happen around or on March 20 and Sept. These shifting dates are because an Earth year is not exactly days: There is an extra quarter of a day 6 hours that accumulates each year, causing the date of the equinox to shift. The planet's orientation towards the sun is also constantly shifting, tweaking the timing of the equinox.

Related: Why the autumnal equinox doesn't fall on the same day every year. The equinoxes mark the astronomical beginning of spring or autumn, depending on the hemisphere. However, the meteorological beginning of these seasons is March 1 and Sept. In the Northern Hemisphere, the March equinox heralds the beginning of spring, and is referred to as the spring or vernal equinox vernal comes from the Latin term "ver" for spring.

At the same time, the Southern Hemisphere shifts into autumn. The converse is true in September, when the northern half of the planet descends into the colder months of autumn and the southern half enters spring. Earth is not alone in experiencing equinoxes. It is based on the concept of a continuous struggle between Ormazd or Ahura Mazda , the god of creation, light, and goodness; and Ahriman, the spirit of evil and darkness.

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Jeannie Evers, Emdash Editing. Caryl-Sue, National Geographic Society. For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher.

They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource. If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media. Text on this page is printable and can be used according to our Terms of Service. Any interactives on this page can only be played while you are visiting our website.

You cannot download interactives. A season is a period of the year that is distinguished by special climate conditions. The sun is an ordinary star, one of about billion in our galaxy, the Milky Way. The sun has extremely important influences on our planet: It drives weather, ocean currents, seasons, and climate, and makes plant life possible through photosynthesis.

Join our community of educators and receive the latest information on National Geographic's resources for you and your students.

Skip to content. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. The equinoxes are the only time when both the Northern and Southern Hemisphere s experience roughly equal amounts of daytime and nighttime.

On Earth, there are two equinoxes every year: one around March 21 and another around September The March equinox is the vernal equinox in the Northern Hemisphere, and the autumnal equinox in the Southern. The September equinox is the autumnal equinox in the Northern Hemisphere and the vernal in the Southern.

Solar declination describes the latitude of the Earth where the sun is directly overhead at noon. So, equinoxes are the only times of the year when the subsolar point is directly on the Equator. The subsolar point is an area where the sun's rays shine perpendicular to the Earth's surface—a right angle. Only during an equinox is the Earth's