The summer solstice officially begins today, June 21, at 15:24 Vietnam time. This astronomical event marks the longest day of the year in the Northern Hemisphere. While the solstice typically occurs on June 21, the date can occasionally shift. According to the report, it will be an exceptionally long wait before the solstice falls on June 22 again. Specifically, the international date for the summer solstice will not be June 22 until the year 2203. This means it will take another 177 years for that specific calendar alignment to recur. The phenomenon highlights the complex relationship between the solar year and the calendar.