First Day of Spring 2016: Vernal Equinox

When does spring 2016 begin? On this page, get informed about the vernal equinox, spring weather—and a solar eclipse!

 

In the Northern Hemisphere, spring begins with the equinox on the 20th March at 6:29 a.m. (EDT).

• Astronomically speaking, the equinox occurs when the Sun crosses the celestial equator on its way north along the ecliptic.  This March equinox is also known as the vernal, or spring, equinox, and marks the start of the spring season.
• Meteorologically speaking, however, in the Northern Hemisphere the official spring season always begins on March 1 and continues through May 31. Summer begins on June 1; autumn, September 1; and winter, December 1.

Weather scientists divide the year into quarters this way to make it easier to compare seasonal and monthly statistics from one year to the next. The meteorological seasons are based on annual temperature cycles rather than on the position of Earth in relation to the Sun, and they more closely follow the Gregorian calendar. Using the dates of the astronomical equinoxes and solstices for the seasons would present a statistical problem because these dates can vary slightly each year.

The Vernal Equinox

The word equinox is derived from the Latin words meaning “equal night.” All over the world, days and nights are approximately equal. Today, the Sun rises exactly in the east and sets exactly in the west.
At the equinoxes, the tilt of Earth relative to the Sun is zero, which means that Earth’s axis neither points toward nor away from the Sun. (However, the tilt of Earth relative to its plane of orbit, called the ecliptic plane, is always about 23.5 degrees.)
Enjoy the increasing daylight!  See how your day “grows” with our personalized Sun rise and set calculator.

Equinox Facts

Question: Why doesn’t the vernal equinox (equal night) on March 20 have the same number of hours for day and night?
Answer: Our former astronomer, George Greenstein, had this to say: “There are two reasons. First, light rays from the Sun are bent by the Earth’s atmosphere. (This is why the Sun appears squashed when it sets.) They are bent in such a way that we are actually able to see the Sun before it rises and after it sets. The second reason is that daytime begins the moment any part of the Sun is over the horizon, and it is not over until the last part of the Sun has set. If the Sun were to shrink to a starlike point and we lived in a world without air, the spring and fall equinoxes would truly have ‘equal nights.’”

 

Equinox Folklore

Question: According to folklore, you can stand a raw egg on its end on the equinox. Is this true?
Answer: One spring, a few minutes before the vernal equinox, several Almanac editors tried this trick. For a full workday, 17 out of 24 eggs stood standing. Three days later, we tried this trick again and found similar results. Perhaps 3 days after the equinox was still too near. Try this yourself and let us know what happens!

Spring Verse

One swallow does not make a spring.
Bluebirds are a sign of spring; warm weather and gentle south breezes they bring.
In spring, no one thinks of the snow that fell last year.
Don’t say that spring has come until you can put your foot on nine daisies.
Spring-time sweet!
The whole Earth smiles, thy coming to greet.

Signs of Spring

The vernal equinox signals the beginning of nature’s renewal in the Northern Hemisphere. Worms begin to emerge from the earth, ladybugs land on screen doors, green buds appear, birds chirp, and flowers begin to bloom.