What is a solstice?

Happy Summer everyone! Even though warm days came back for a while for many of you, summer officially starts today, June 20th¹. This day is also known as the summer solstice, but why we call it like that, and what happens today? Let’s find out, as always, together.

The word solstice comes from the combination of the latin words sol (sun) and sistere which is translated mainly with the expression “to stand still” but I prefer to use the verb “to stop”. That’s because, in the northern hemisphere, this will be the day with the longest daylight of the year, and so I like to think of the Earth that stops by her old friend Sun, before going back on its long journey around it.

First, we need to understand that our Planet doesn’t stand up straight: its axis, around which the Earth rotates, has an inclination of approximately 23.5°. This is why we have seasons: at any given time, the northern hemisphere has the opposite season of the southern hemisphere, because it’s either inclined towards the sun or not, and so will be hit by sun rays more or less directly.

Travelling around the sun, in two moments of the year, one of the Poles will have the closest inclination towards the Sun and these are the days we call solstice. But remember: the day you welcome summer, your Australian friends will prepare for winter!

Not sure yet? Let’s look at the next image.

 I designed it to represent the two moments of the year. As you can see, on the 21st of June the North Pole has the maximum inclination towards the Sun, while on the 21st of December the situation is the opposite.

There are two other key moments of the Earth’s journey around the Sun: these are the days called the equinox, and they happen respectively on the 20th March and the 22nd of September. For now, let’s focus our attention on the solstice only and let’s postpone the explanation of the equinox for a more appropriate time.

How will you be welcoming the summer? Let us know in the comments and don’t forget to stay Green!

NOTE ¹: Normally, the summer solstice in the northern hemisphere is on the 21st of June. This year went on a day earlier because we’re on a leap year, explanation of the implications and meanings of this particular year will be postponed to one of our next stories.

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