Depending on your location, the equinox can be seen as a harbinger of long nights and gloomy weather or a promising beacon of cooler temperatures and more sunshine. Observing and predicting the equinoxes is one of the earliest skills in humanity’s astronomical toolkit. Many ancient observatories around the world observed the more obvious solstices as well as the equinoxes. These days, you don’t need your own observatory to know when the equinox occurs, because you’ll see it marked on your calendar twice a year! The word “equinox” originates from Latin, and is translated as Equal (Even-) Night (-nox). But what exactly is the equinox?
One equinox Happens twice every year in March and September. In 2026, the equinox will occur on March 20 at exactly 14:46 UTC (or 7:46 a.m. EDT), and again on September 23 at 00:05 UTC (or September 22, 2026, 5:05 p.m. PDT). The equinox marks the exact moment when the center of the Sun crosses the plane of our planet’s equator. On the day of the equinox, observers at the equator will see the Sun directly overhead at noon. After the March equinox, observers anywhere on Earth will see the Sun’s path across the sky continue to move north each day until the June solstice, after which it begins to travel south. The Sun crosses the equator again during the September equinox, and continues to travel south until the December solstice, when it returns north once again. Because of this movement some people call the March equinox retrograde equinox and as the September equinox southern equinox.
Our Sun shines equally on both the Northern and Southern Hemispheres during the equinox, which is why it is the only time of year when Earth’s North and South Poles are simultaneously illuminated by sunlight. In particular, the lengths of day and night are not exactly equal at the equinox; The date of that division depends on your latitude, and may be a few days before or after the equinox. Complicating factors? Our sun and atmosphere! The Sun itself is a sphere, not a point light source, so its edge is refracted by our atmosphere as it rises and sets, adding several minutes of light to each day. The Sun does not turn on and off clearly at sunrise and sunset like a light bulb, and so there is no perfect division of day and night at the equinox – but it is very close.
The equinoxes are associated with the changing seasons. In March, Northern Hemisphere observers welcome longer, warmer days heralding their Vasanthior spring, the equinox, but Southern Hemisphere observers note the shorter days – and long, cool nights – that are their sign. of autumnOr autumn, equinox. Come September, the opposite is true.
Originally posted by Dave Prosper: February 2022
By Kat Troche Last updated: March 2026
(tagstotranslate)Night Sky Network