1. Winter Solstice:
During the winter solstice, which usually occurs around December 21st, the Northern Hemisphere is tilted furthest away from the sun. This results in the shortest day and longest night of the year in the Northern Hemisphere. In contrast, the Southern Hemisphere experiences the summer solstice with the longest day and shortest night of the year.

2. Spring Equinox:
The spring equinox typically falls on March 20th or 21st when both hemispheres receive equal amounts of sunlight. Day and night are approximately equal in length during this time, marking the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere. This is a time of balance and transition between the seasons.

3. Summer Solstice:
Around June 21st, the Northern Hemisphere experiences the summer solstice when it is tilted closest to the sun. This results in the longest day and shortest night of the year in the Northern Hemisphere, while the Southern Hemisphere has its winter solstice with the shortest day and longest night. It is the peak of summer in the Northern Hemisphere.

4. Fall Equinox:
The fall equinox, occurring around September 22nd or 23rd, marks the beginning of autumn in the Northern Hemisphere and spring in the Southern Hemisphere. Day and night are once again approximately equal in length during this time, signaling the transition from summer to winter in the Northern Hemisphere and from winter to summer in the Southern Hemisphere.