When is the first day of spring? The Science Behind Next Week’s Equinox (And Why It’s Great For Stargazing)

When is the first day of spring? You’ve heard of equinoxes. It happens every year. More precisely twice. But do you understand? could you explain it to a child

Here’s everything you need to know about the vernal or vernal equinox in 2023—when it is, what it is, and why it’s a great time for stargazing this year.

When is the vernal equinox?

This year, the vernal equinox – the beginning of astronomical spring in the northern hemisphere – occurs on Monday, March 20 at 21:25 UTC. Translated, this means these times in North America:

  • 5:25 p.m. EDT
  • 4:25 p.m. CDT
  • 3:25 p.m. MDT
  • 2:25 p.m. PDT
  • 1:25 p.m. AKDT
  • 12:25 p.m. HDT

What is the vernal equinox?

It is one of four markings of the Earth’s annual orbit around the Sun. Like the other equinox at the end of September, it marks a moment when the sun is above the equator, bringing equal night and day to both hemispheres (equinox is Latin: even (same) and nox (Night).

The vernal equinox is when the Sun crosses the celestial equator heading north, marking the transition from winter to spring in the Northern Hemisphere and from summer to autumn in the Southern Hemisphere.

The other two markers are the late June and late December solstices, which mark the days with the longest daylight and darkest days, respectively.

Why do equinoxes occur?

Equinoxes and solstices mark the beginning and end of the seasons. The seasons are the direct result of our planet’s tilted axis, which changes the amount and intensity of sunlight bestowed on each hemisphere. Summer in the northern hemisphere – marked by the June solstice – is when that half of the planet is tilted toward the sun. The days are getting longer and more sunlight is reaching them. Winter is the opposite.

Equinoxes are when the planet is sideways to the Sun – when the tilt of the Earth’s axis is not tilted toward or away from the Sun, sending equal amounts of daylight and darkness to all parts of our planet.

Why is this equinox a great time for stargazing?

A new moon occurs the very day after the vernal equinox at 17:23 UTC. Since a new moon is roughly between the earth and the sun, it is completely invisible and its light never shows it in the night sky. This will make the night as dark as possible. It makes a world of difference when trying to find faint star clusters and constellations.

As the weeks after the equinox draw in, the days grow longer than the nights — culminating in the solstice, the longest day of the year — making stargazing increasingly difficult, especially for those in northern latitudes, where June is never gets really dark. However, the equinox itself is an excellent time for stargazing this year, as the night sky will be darker than ever.

How to see the equinox

Not much to see that the sun is directly over the equator, is it? The best way to “see” an equinox or solstice is to watch it at sunrise or sunset. Only on an equinox does the sun rise due east and set due west, which has meant something to many ancient cultures over the centuries.

Not only can you watch the sunrise and sunset with the cardinal points, but you can also travel to an ancient place to see the different orientations. These locations include, but are not limited to:

  • Stonehenge and Avebury, England
  • Newgrange, Ireland
  • Chichen Itza, Mexico
  • Machu Picchu, Peru
  • Temples of Karnak, Egypt

During Earth’s annual orbit around the Sun, different parts of the planet receive different amounts of sunlight—except at the equinoxes. People have known this for thousands of years and celebrate the changing of the seasons. How will you mark the same day, same night?

I wish you clear skies and big eyes.

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