Although it is common to talk about the day of the summer solstice, this event occurs at a specific moment. The day and moment are different every year. Since the year does not last for a whole number of days, the summer solstice falls on June 20-22. In 2025, it falls on June 21, at 2:42 a.m. GMT (on June 20, at 9:42 p.m. EST).
It is at this moment that the northern hemisphere receives the greatest amount of sunlight and heat, while the southern hemisphere receives the least. The phenomenon is because the Earth, like a gyroscope or a spinning top, maintains the direction of its rotation axis relative to distant stars (although on the scale of thousands of years, the axis changes direction – phenomena known as precession and nutation). As a result, there are two times during the year when both hemispheres are equally illuminated (equinoxes) and two more when one of them receives significantly more energy (solstices).
The summer solstice is the longest day of the year for us, when the Sun is at its highest in the sky. For example, in Kyiv, the daylight hours will last almost 16 hours and 27 minutes. In addition, this day marks the beginning of the astronomical summer, which will last until the autumnal equinox on September 22.
