Stonehenge during the summer solstice © Getty Images

Summer solstice: five big questions

Around 20/21 June every year the Sun appears to hang longer in the sky than any other - here's what makes the summer solstice so magical (according to science).

1

Is solstice a scientific term?

Yes, a solstice is an astronomical event that happens twice a year. During the solstice, the tilt of the Earth’s axis is most inclined towards the Sun, causing it to reach its highest point visually in the sky. This means it takes the most amount of time to cross the sky. The word solstice is derived from the Latin sol (sun) and sistere (to stand still).

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2

What do you mean the Sun ‘stands still’?

At the solstices, the Sun stands still in declination (declination is the number of degrees north or south an object is from the celestial equator.) It has reached its highest point in the sky, and from now until the Winter solstice, its highest point begins to drop each day. This means it appears to ‘stand still’ for a few days while its progress in the sky changes direction.

3

How much longer is the day compared to other days?

A matter of seconds. In the UK we get 16 hours, 38 minutes and 22 seconds of sunlight, which is a whopping three seconds more than the day before. But the day after will have three seconds less. Soak it up.

4

Why isn’t it the hottest day of the year?

Although the Sun is out for longer than on any other, you may have noticed that June isn’t the best time to bare your bathing suit. An astronomer will tell you that this is definitely the start of summer, but the heat of the oceans drives a lot of the weather on land. It takes a while for the water to heat up which is why the hottest days tend to be later in the year.

5

Why isn’t it the longest day everywhere in the world?

Because the Earth is wonky, which is what gives us the seasons. It’s tilted on its axis at an angle of 23.5 degrees, meaning that as it moves around the Sun different parts of the globe receive varying amounts of sunlight over the year. The summer solstice is the longest day for the northern hemisphere as the Earth’s position means our hemisphere leans towards the Sun, receiving the most sunlight.


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