Summer begins in the Northern Hemisphere on Friday, June 20, at 10:42 p.m. Eastern Daylight Time. This annual event, known as the June solstice, marks a specific point in Earth’s orbit. And it happens because our planet is tilted.
Earth maintains a tilt of approximately 23.5° on its axis. As the planet orbits the Sun, this tilt causes different hemispheres to receive varying amounts of direct sunlight throughout the year. During the June solstice, the Northern Hemisphere is angled most directly toward the Sun. Consequently, sunlight reaches this region at its steepest angle, leading to the longest period of daylight experienced during the year. For locations situated north of the Arctic Circle, this alignment results in the phenomenon known as the “midnight Sun,” where the Sun remains visible throughout the night. Conversely, the Southern Hemisphere experiences its winter solstice at this time, receiving the least direct sunlight and its shortest day of the year.
The term solstice originates from the Latin words “sol,” meaning Sun, and “sistere,” meaning to stand still. This refers to the Sun’s apparent stationary position in its northward (or southward) movement across the sky for a few days before it begins to reverse its direction. If you observe the Sun on the horizon several days before and after the solstice you’ll see little change in its rising and setting points.
Just as a side note, most people call this event the summer solstice. That’s technically only correct for those of us living in the Northern Hemisphere. South of the equator, it’s the winter solstice. So, to prevent confusion, astronomers just use the month name.
Historically, the June solstice has held significant importance for various human cultures. Ancient civilizations, including those responsible for the construction of Stonehenge in England, aligned structures to observe the Sun’s position during the solstice. These alignments show that ancient peoples used the solstice as a marker for calendars and for timing agricultural activities. Traditional celebrations and rituals often coincided with this day, recognizing the change in seasons. Modern interpretations continue to acknowledge the solstice as a marker of the annual cycle and a point of seasonal transition.
The June solstice provides a clear demonstration of Earth’s orbital mechanics and axial tilt. It is a predictable astronomical event that underscores the dynamic relationship between our planet and the Sun, influencing daily light cycles across the globe. It’s not something we can observe, but it’s important, nonetheless. So, happy solstice!
