(WHTM) — On March 20, at 5:24 p.m. Eastern Daylight Time (EDT), the spring equinox will occur. Then, the summer solstice will occur on June 21 at 10:57 a.m. EDT.
So, why is one called a solstice and one called an equinox? It all has to do with the Sun and the Earth’s tilt.
The March equinox marks the sun’s crossing above the earth’s equator – moving from south to north. It makes the beginning of spring in the Northern Hemisphere, while the Southern Hemisphere will start the autumn season.
The word equinox comes from two words of Latin origin with the roots aequus meaning “Equal” and nox meaning “Night.”
The Solstice on the other hand is the point where the Sun appears to reach either its highest or lowest point in the sky for the year, and thus ancient astronomers came to know the day as one where the Sun appeared to stand still, according to the Franklin Institute.
The word solstice comes from the Latin words sol for Sun and sister for “to stand still.”
These occurrences happen because of the Earth’s tilt. The axis of the Earth is not oriented vertically but it is tilted at a 23.5-degree angle. Because of this tilt, and due to the Earth revolving around the sun, this causes seasonal changes.
If the axis was not tilted, the year-round climate would be rather boring and many places on Earth wouldn’t receive much light.