0. The summer solstice occurs on
The summer solstice in the Northern Hemisphere occurs on or around June 21. It is the longest day of the year, when the sun is at its highest point in the sky and directly overhead at the Tropic of Cancer (23.5°N latitude).
A. March 21
Incorrect. This is the date of the spring (vernal) equinox.
B. April 21
Incorrect. This date has no astronomical significance related to solstices or equinoxes.
C. May 21
Incorrect. This is before the actual solstice occurs.
D. June 21
Correct. This marks the summer solstice in the Northern Hemisphere.