The June Solstice, June 21

Today, the northern hemisphere of the Earth is most tipped toward the Sun. It is the first day of summer in the northern hemisphere, and the first day of winter in the southern hemisphere. The northern hemisphere is receiving the most sunlight at this time of year, so it is warming up, even though we are actually farther from the Sun now than in our winter.

This day is often called the Summer Solstice, but since it is also the Winter Solstice in the southern hemisphere, that can be confusing. Sky and Telescope therefore now refers to it as the "June Solstice" to avoid confusion.