At 11:44 pm on June 20 we officially enter the summer, with the arrival of the solstice. More properly, the summer solstice arrives and leaves practically immediately, substantially representing an instant, as it happens for the equinoxes.

The instant of the summer solstice is that in which the northern hemisphere appears more inclined towards the Sun than any other moment, recalls the Noaa. Always celebrated in different areas of the world, the summer solstice however, it has now become synonymous with a day, they also remark from the Royal Museum of Greenwich, recalling the celebrations that take place on the occasion in nearby Stonehenge (but not only). And 2020 will also be a somewhat special summer, because on June 21 an annular eclipse of the Sun falls.

1. If we were in Space we would thus see the solstice

The shot was captured by the Goes East satellite and shows our planet just before the summer solstice, that of last year. The North Pole appears completely illuminated, while the South Pole lies in the shade. The situation is reversed – from north and south – on the occasion of the winter solstice.

(photo: Noaa Environmental Visualization Laboratory)

Spreading the gaze all year long, some time ago NASA published an animation showing the Earth during the changing seasons , where you can clearly see how the line of shadow that separates the day from the night during solstices moves and equinoxes.

2. Mars also has its own, and it looks like this

The seasons are not a prerogative of the Earth, each planet has. By analogy with what is observed for our planet, we speak of summer solstices for the other bodies of the Solar System when the north pole is inclined towards the Sun, and of winter solstice as it is the south pole. But notable are the differences with Earth. On our planet the seasons are determined by the inclination of the Earth’s axis with respect to the plane of the orbit around the Sun and the small eccentricity of this orbit (only weakly elliptical) has practically no effect on our climate .

Generally, however, these two factors determine the planetary seasons, explains NASA: the inclination of the axis and the distance from the Sun (although obviously other factors, such as the atmosphere, influence the climate). When we combine the inclination of the planetary axis pronounced with the variation of the distance from our star, the planets can experience rather pronounced seasonal changes. As happens to neighbouring Mars. Here the seasons last on average twice as long as the terrestrial ones.

The NASA Phoenix Mars Lander spacecraft in 2008 managed to capture the day of the Martian summer solstice, capturing a colour image of the planet. Here she is.

solstice mars
(photo: NASA / Jpl-Caltech / University of Arizona / Texas A&M University)

3. It doesn’t always happen on the same day in June

As with the other seasons, the day of the summer solstice (again, when we go through it) can change. So if this year this moment almost falls between  June 20 and June 21 , in 2020 it will be in the early morning of the 21st, while in 2024, the summer will return earlier, on June 20.

4. It is not the hottest day of the year

The first day of summer, the longest day of the year. The one in which the amount of solar radiation received from the northern hemisphere reaches its maximum. But it’s not the hottest day of the year, why? The answer has to do with the fact that the Earth , the atmosphere and the oceans take a while to warm up and release heat . Or rather, explains Jagadheep D. Pandian on Ask an Astronemer , an initiative of the astronomy department of Cornell University:“In the northern hemisphere, the amount of heat received by the Earth from the Sun slowly increases near the summer solstice. Proceeding towards the summer, the heat received during the day is greater than the heat radiated during the night and so the average of the temperatures slowly increases. The heat input is at its maximum for the solstice and decreases thereafter, but the heat input rate is even greater than the dissipation rate. This is why the average temperature increases after the solstice and it is only later in the year that it will begin to decrease . ” This phase shift between solstice and warmer days is sometimes known as seasonal lag .

5. Party in a lot of places around the world (not just in Stonehenge)

It is certainly one of the most famous places in the world to celebrate the summer solstice and the arrival of the summer, but Stonehenge is certainly not the only one . Appointments aside to observe the alignment of the rising or setting sun, around the world we remember several celebrations related to the summer solstice, such as the Scandinavian Midsummer or the Kupala Night in the countries of Eastern Europe, or the fires of the solstice in Tyrol.