Why is June 21 Summer Solstice the Longest Day of the Year?

Why is June 21 Summer Solstice the Longest Day of the Year?
Why is June 21 Summer Solstice the Longest Day of the Year?

We may have read about summer solstice in our science, geography or environmental science books at school. But, do we really know that why is June 21 the longest day of the year. Read on to discover interesting facts about the summer solstice.

The universe bears weird phenomenon. Why does earth revolve around the sun? Why does a day have 24 hours? Why are the poles cold and the equator belt toasty? We may not know the secret behind these natural processes, but the scientists and researchers make efforts to unveil the reason behind it. Not all of us know that June 21 is observed as the summer solstice: the longest day of the year when the duration of the day is longer than night.

In case you missed it, here are some cool facts about summer solstice that you ought to know.

The science behind Summer solstice.
The science behind Summer solstice.
  1. Summer Solstice marks the Beginning of the Summer Season in the Northern Hemisphere.

Both meteorologists and astronomers hold different views in this regard. The astronomers believe that the June Solstice on June 21 marks the onset of summers in the North and the winters in the South. Contrary to this, the meteorologists study the conditions that lead to summer. For them, the season began on June 1, when temperatures on the earth surface started rising in the northern hemisphere.

  1. Contrary to what we think, the Earth is the Farthest from the Sun on June 21.

People think that since June 21 is the longest day of the calendar, the earth must be really close to the sun. It is not so, in fact, the earth is on its Aphelion, a few weeks after the summer solstice. In simpler words, our planet is farthest from the sun, which makes us think then why is it hot then? It’s because the seasons have very little to do with the distance of a planet from the sun.

In reality, it’s the tilt of a planet’s rotational axis (that is 23.4 degree) which is responsible for the onset of different seasons. The orientation of Earth’s axis changes when the planet moves on its orbit. Therefore, the northern hemisphere faces the sun on June Solstice, thus experiencing summers whereas the southern hemisphere tilts away from the sun, thus experiencing winters.

  1. June 21 is the Day of Midnight Sun (24-hour Sunlight) at the Arctic Circle.
Midnight Sun: The appearance of multiple suns at the Arctic Circle, occurring due to refraction of sunlight.
Midnight Sun: The appearance of multiple suns at the Arctic Circle, occurring due to refraction of sunlight.

On this day, the countries falling in the Arctic Circle receives 24-hour daylight. At the same time, the Antarctic Circle experiences ‘Polar Night’ (24-hours of the night) at June Solstice. Due to atmospheric refraction, the sun is visible at midnight on the Arctic pole a few days before the onset of June Solstice. As we move towards the north from the Arctic Circle, the duration of Midnight sun increases with each passing day.

Polar Night in the Southern Hemisphere.
Polar Night in the Southern Hemisphere.
  1. June 21 is not the Hottest Day of the year.

Contrary to the popular public notion, June 21 is not the hottest day of the year. It’s because post-solstice it takes time for the land and the oceans to warm up. Thereafter, the air above the land and the ocean heats up thus causing hot, intense summer days a few days after the solstice. This is what we call as ‘lag or delaying of seasons’.

  1. June Solstice Needn’t Fall on June 21.

Unlike our birthdays, summer solstice needn’t fall on the same day every year. In fact, it depends on the pattern followed by the Earth while moving around the sun. It can fall on any day between June 20 and 22. For instance, the solstice of 2975 fell on June 22. It’ll fall on the same day in 2203.

Hopefully, these facts will help you understand the logic behind summer solstice. Check out the internet for more details, you might uncover something interesting!

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