Longest and shortest days
The solstices causes the shortest and longest days of the year.A solstice is an astronomical event that happens twice each year, when the tilt of the Earth's axis is most inclined toward or away from the Sun, causing the Sun's apparent position in the sky to reach its northernmost or southernmost extreme.The solstice days are thus those when the daylight hours are at their longest or shortest. When the Sun is over the northern Tropic of Cancer, the northern hemisphere experiences the longest day and shortest night. When it is over the southern Tropic of Capricorn, the northern hemisphere has its shortest day and longest night.
The exact solstice dates vary from year to year, in the northern hemisphere the longest day is usually June 21st and the shortest day December 21st.
On the two days of the year when the sun is over the equator at noon, the Earth has days and nights of equal lengths - these are the equinoxes.