Shop Windows to the Universe

Become a nitrogen atom in the nitrogen cycle in our Traveling Nitrogen Classroom Activity Kit/Game. See all our games, activity kits and classroom activities.
A diagram showing how the Sun moves through the sky on an equinox.
Click on image for full size

The Vernal and Autumnal Equinoxes

We're still pretending that you're the person standing on the Earth in the picture to the left, living in Topeka, Kansas, around 40° N latitude. The picture on the left shows the view from the solar system (upper panel), and from on the surface of the earth (lower panel). Notice that some of the same features are labeled on each panel. In the upper panel, the Earth's axis is pointing into your computer screen.

The upper panel shows that on an equinox (which occurs around March and September 21), neither half of the Earth points directly towards the Sun. In fact, the Sun is at the equator, so both halves of the Earth are getting about the same amount of sunlight. For you in Topeka, the altitude of the Sun is about 50°, in between its altitude on the solstices. The bottom panel shows how this looks to someone standing on the ground in Topeka.

Equinox literally means "equal night". On the vernal (spring) and autumnal (fall) equinoxes, day and night are nearly the same length (the date on which day and night are actually closest to the same length is called the equilux, and occurs a few days towards the winter "side" of each equinox). Neither hemisphere gets more sunlight than the other, so both have similar seasons (fall in one hemisphere and spring in the other).

How high the Sun gets in your sky, and how long it is above the horizon during the day, depend not only on the season, but also on your latitude.

Last modified September 3, 2010 by Randy Russell.

Shop Windows to the Universe Science Store!

The Fall 2009 issue of The Earth Scientist, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

President of Peru Visits Ancient Incan Sites

Peru's new president, Alejandro Toledo, was sworn in on July 28, 2001. The next day he took part in traditional ceremonies asking for the blessing of the Incan gods. Toledo is himself one of 16 children...more

Cuzco

This is an aerial view of Cuzco. In the center of the picture, the cathedral of Cuzco can be seen. This cathedral was built in the 17th century. Cuzco is located in Southern Peru. It is the ancient capital...more

Native American Astronomy

By 30,000 B.C,. Asian hunter-gatherers had crossed the Bering Strait into North America. These people were the first to inhabit this new land and so they are known as the Native Americans of North America....more

Archeoastronomy

"The movements of the heavenly bodies are an admirable thing, well known and manifest to all peoples. There are no people, no matter how barbaric and primitive, that do not raise up their eyes, take note,...more

The Stones of Carnac

The stones of Carnac, France, are probably the most famous stones markings outside of those found at Stonehenge in England. Where Stonehenge is composed of standing stones, the Carnac area has many different...more

The Cairns of Clava

Not too far from Loch Ness, where the green highlands of Scotland rise and fall there lies three giant cairns of stones. They are called the Balnuaran of Clava. The Balnuaran of Clava, giant tombs encased...more

The Stones of Fossa

The stone structures of England and France are very famous. But, one can also find stone rings, tombs, and dolmen structures in present-day Italy. One such megalithic structure is a site in Fossa, Abruzzo....more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF