What is defined as the longest day of the year in the Northern Hemisphere?

The longest day of the year in the Northern Hemisphere is known as the Summer Solstice. This event occurs around June 21st each year when the Earth's axial tilt is such that the North Pole is tilted closest to the Sun. As a result, locations in the Northern Hemisphere experience the most daylight hours, with the Sun reaching its highest point in the sky at noon.

This phenomenon is a significant astrological event because it marks the transition into summer, affecting weather patterns, ecosystems, and even cultural events and celebrations. In contrast, the other options refer to different events in the annual cycle: the Winter Solstice represents the shortest day of the year, while the Vernal and Autumnal Equinoxes mark moments when day and night are approximately equal in length.