Final answer:
The Sun spends about six months north of the celestial equator, from March 21 to September 21, and approximately six months south of the celestial equator, from September 21 to March 21, resulting in varying daylight hours for different hemispheres.
Step-by-step explanation:
The Sun is north of the celestial equator from about March 21 to September 21. During this period, it spends approximately six months favoring the Northern Hemisphere. The Sun's path in the sky causes it to rise north of east and set north of west around June 21, resulting in about 15 hours of daylight in the United States.
Conversely, when the Sun is south of the celestial equator, it favors the Southern Hemisphere, spending around six months from approximately September 21 to March 21. The Sun then rises south of east and sets south of west around December 21, providing only about 9 hours of daylight in the United States. At the North Pole, this results in 6 months of continuous sunlight followed by 6 months of darkness.
On the equinoxes, which occur around March 21 and September 21, the Sun is on the celestial equator and provides approximately 12 hours of daylight and 12 hours of night to every place on Earth. As such, these dates mark when the Sun transitions between being north and south of the celestial equator.