Today is the Vernal Equinox, the first day of spring in the northern hemisphere. The new season officially began at 16:57 UTC, which is 12:57pm Eastern Daylight Time.

The astronomical seasons are produced by the tilt of the Earth’s axis – a 23.5° angle – and the movement of the planet around the sun. Today, as spring begins, the Earth’s axis is tilted neither toward nor away from the sun.  This position distributes the sun’s energy equally between the northern and southern hemispheres.

Since the winter solstice in December, the sun has been making an apparent northward journey in our sky toward the Tropic of Cancer.  Today, it crossed the equator. This means we have approximately equal hours of day and night. The word “equinox” is derived from Latin and means “equal night”.

As a transitional season, spring marks the end of winter’s biting chill and the gradual return of warmth.  It is often associated with the ideas of renewal and rebirth.  As such, it has long been a cause for celebration across many cultures throughout human history.

Earth’s solstices and equinoxes. Image Credit: NASA

The Earth’s axis is tilted neither toward nor away from the sun on the Vernal Equinox. Image Credit: NASA