In Mexico, June 20 will be the longest day of the year and also the shortest night. And it is that on that date the summer solstice will take place in the northern hemisphere, an astronomical phenomenon that will end spring and mark the beginning of the new season.
According to the Institute of Astronomy of the National University of Mexico (UNAM), the astronomical event will take place specifically at 9:32 p.m. central time.
Due to the inclination of the Earth’s axis, that day the north pole of our planet will be pointing more directly towards the Sun than at any other time in 2021, giving rise to the summer solstice in the northern region. But what is this event specifically, and why does it affect the duration of the days and nights?
Summer solstice
The axis of the Earth is an imaginary pole that crosses our planet from top to bottom. As we know, our world turns on that imaginary line, completing one revolution in 24 hours; And that’s how the days and nights happen.
According to NASA, Earth’s axis is always inclined 23.5º with respect to the Sun. This position causes the amounts of sunlight that our planet receives to be different in each region, as the Earth advances through its orbit.
When the North Pole points towards the Sun, the South Pole automatically tilts in the opposite direction. This makes summer begin in our hemisphere, and winter in the southern hemisphere.
“During the summer, the north pole leans towards the Sun and the south pole leans away from the sun. The northern summer solstice is a time when the North Pole of the Earth points more directly towards the Sun than at any other time of the year ”, explains NASA.
On June 20, the north pole will reach its maximum inclination towards the Sun, the day will be the longest of the year, and the night, the shortest. However, this does not imply that it will be the hottest day of 2021 in the hemisphere. Although the Earth will absorb a lot of sunlight during the summer solstice, it takes time for the oceans to warm up, so the difference in temperatures begins to be appreciated weeks later, between July and August.
“The oceans are slow to warm and remain cool, resulting in a moderating influence on temperature variations,” explains the US space agency on its website.
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It also does not mean that our world is closer to the Sun. In fact, the Earth reaches the point of its orbit closest to the sun in January.
“The Earth is closest to the Sun between January 3 and 5. The difference is a small percent of distance, too small to be seen”, indicated NASA.
The summer solstice in the northern hemisphere only implies that this area of the Earth is more tilted towards the sun. For this reason, it receives more sunlight and temperatures increase as the weeks go by. This means that during the boreal summer the Arctic Circle is always illuminated, 24 hours a day and that in countries such as Finland and Norway it is daylight early and it gets dark very late, registering few hours of darkness.
