In this article
What happens in the sky
Seen from Earth, the Sun travels along a path called the ecliptic, which is tilted against the celestial equator. At the March equinox the Sun passes from the southern half of the sky to the northern half. At that instant it rises almost due east and sets almost due west for every observer.
From here the days lengthen in the north and shorten in the south, until the June solstice turns the trend around.
Equal day and night, roughly
The word equinox means equal night. In practice the match is only approximate. Sunrise is counted from the top edge of the Sun, and the atmosphere bends its light so that we see it slightly before it truly clears the horizon. Both effects add a few minutes of daylight, so the real day of equal length, the equilux, arrives some days before this equinox in the north and after it in the south.
Which season is it where you live?
In Europe, North America and most of Asia this is astronomical spring. In Australia, New Zealand, South Africa and most of South America it marks the start of autumn. Meteorologists count seasons by whole months, so they began spring or autumn on 1 March, but astronomers wait for the Sun itself.
Customs at the equinox
- Nowruz. Persian communities from Iran to Central Asia begin their new year at this moment, with a table of symbolic foods.
- Chichén Itzá. In Mexico, the afternoon light makes a serpent of shadow appear to slide down the stairs of the El Castillo pyramid around the equinoxes.
- Higan. In Japan, a week of remembering ancestors is centred on the equinox.
- Astrology. By tradition the tropical zodiac begins here, at 0 degrees of Aries, which makes it a symbolic new year for the signs.
Look at the sky yourself
Note where the Sun rises on the horizon this week, then check again at the next solstice. The change is easy to see over a few months. For a lunar view of the same season, the Moon phases hub shows the current phase, and the equinoxes and solstices hub lists all four turning points.
Questions people ask
Is the March equinox the first day of spring?
Astronomically, yes, in the northern hemisphere. In the southern hemisphere it is the first day of autumn.
Why is the date sometimes 19, 20 or 21 March?
The moment of the equinox shifts by about six hours a year and resets in leap years, and your time zone decides which calendar day it lands on.
Can you balance an egg only on the equinox?
No, that is a popular myth. An egg can be balanced on any day with patience, because the Sun's position has no effect on it.