The summer solstice (midsummer), occurs when the earth's tilt on its axis is inclined towards the sun at an angle of 23.4o. The tilt leads to varying durations of sunlight is various parts of the world in the course of the earth's revolution. The summer solstice leads to longer days and shorter nights in the northern hemisphere. The name solstice is a combination of the Latin word "sol," which means sun and the word "sistere," which translates to "standing still." The term describes the unique phenomenon that occurs during the period when the sun's position at noon appears not to shift much. Summer solstice typically occurs between June 20th and 22nd and signals the beginning of summer.
Summer Solstice Does Not Occur Only on Earth
All planets in the solar system experience summer solstice at different periods. For example, the midsummer on Mars is experienced just days after the one on earth.
Prolonged periods of sunlight in the northern hemisphere mean that activities that typically happen during the day can be done at night while daylight is still there. In Alaska, midnight baseball is played to mark the phenomenon.
Distance From the Sun
Among the most popular misconception is that the earth is nearest to the sun during midsummer, (perihelion). In the real sense, during that period the earth's northern hemisphere is furthest from the sun (aphelion).
While the longest day on the equator is typically about 12 hours, the Northern hemisphere can experience days that are far longer. For example, the North Pole can experience as much as 24 hours of sunlight. Areas such as Pennsylvania and northern California experience over 15 hours of daylight while Maine and Washington experience about 16 hours.
Calculation of the Earth's Size
Eratosthenes, an ancient Greek mathematician and astronomer, used the angle of the sun in Alexandria during the summer solstice and the distance between the city and Syene (Aswan) to establish the circumference of the earth. Eratosthenes came quite close to the accurate figure we know today.
The Longest Day in History
The longest day in history was measured in 1912. The day lasted 24 hours and about four milliseconds.
In many cultures, across the world summer solstice was celebrated in various ways. Several ancient structures were also constructed in alignment to the period. For example, in ancient Maya cities, buildings were built such that they aligned to the sun in midsummer. During the period, residents of the cities would gather to witness what appeared to be their king commanding the heavens. The ancient Stonehenge in Britain also has architectural links to the summer solstice.
Higher Amounts of Sunlight Does Not Mean More Heat
Despite receiving long periods of daylight, the northern hemisphere does not experience the hottest day during midsummer. Earth's atmosphere and oceans absorb the sun's rays and release the heat after several weeks.
Absence of Shadows
At noon in areas along the Northern Tropics, shadows cannot be seen.
Happiness and Summer Solstice
A study analyzing posts from 2 million Twitter users found that positive messages were sent out more frequently when days were longer. Other studies found that people exhibited higher happiness levels earlier in the day. One can, therefore, conclude that the levels of happiness are relatively higher during midsummer.