The Summer Solstice

AS if it wasn’t enough that it is so hot these days with the sun shining down so mercilessly on us, now the longest day of the year, June 21, is just days away! Well, it is the longest day for us in the Northern Hemisphere and is called the Summer Solstice, and for those in the Southern Hemisphere, such as in Australia and New Zealand, it is going to be the Winter Solstice and the shortest day of the year. And in the same way that the two hemispheres will have different seasons, in the Arctic, the sun never sets on the Summer Solstice and the Antarctic Circle will not see the sun during this time! Those in the North of the Arctic Circle are able to see the amazing sight of the ‘midnight sun’, when it is visible throughout the night on June 21. This situation is reversed in these places in December when the seasons are reversed, thus in the Antarctic Circle experiences the ‘midnight sun’ around December 22, when it is the Summer Solstice there. Let us now look at what exactly is the Summer Solstice. The word solstice is taken from the Latin word ‘solstitium’, which translates to mean ‘sun-stopping’. Whether the Summer Solstice is occurring in the Northern or Southern Hemispheres, the sun does not rise precisely in the east but rises to the north of east and sets to the north of west which makes it stay in the sky for a longer period of time. Between June and September, the axis of the earth tilts towards the sun, leading to summer in the Northern Hemisphere and winter in the Southern Hemisphere. From December to March the axis points away from the sun so the southern hemisphere enjoys the direct rays of the sun during their summer months. The reason why the June Solstice (let’s call it this here instead of Summer Solstice) occurs is that the sun is at its furthest point from the Equator, at its northernmost point and the North Pole tilts directly towards the sun. Interestingly, the sun is directly over the Tropic of Cancer in the northern hemisphere, passing Mexico, Saharan Africa, and our South Asian region on June 21. No wonder summer is at its peak! The date of June Solstice varies between June 20 and June 22, but June 21 is a more common date for its occurrence. The last time the solstice occurred on June 22 was back in 1971 and the next time it will occur is going to be 2203! Summer Solstice is officially the day marking the beginning of summer in the Northern Hemisphere but this basically holds true for areas that are a little away from the Equator where the four seasons of the year are more marked, e.g. in North America and Europe. In the tropical and temperate regions, the beginning and end of the four different seasons are not so distinctly marked and summer there, like in Pakistan, starts earlier than 21 June. It should be noted that if earth’s rotation was at precise right angles to the plane of its orbit around the sun, there would be no solstice days and no seasons. And also because earth does not move at the same speed when it is moving in its axis. We experience the different seasons is due to the fact that earth spins around its axis — an imaginary line going right through the planet between the North and South Poles – at a tilted angle of around 23.5 degrees off the plane of the earth’s revolution around the sun. As a result, for some months of the year, one half of earth receives more direct rays of the sun than the other half. In addition the movement of Earth around the sun is not a perfect circle but somewhat elliptical due to which the distance between the earth and the sun varies throughout the year, and so does the temperature. And the unequal lengths of the seasons are because earth does not move at a constant speed when it is moving in its orbit around the sun. Spring and summer last longer than autumn and winter in Northern Hemisphere, with the time taken for the sun to move from the March Equinox (March 20) to the June Solstice is roughly 92.8 days, then to the September Equinox (September 22) is 93.6 days, to the December Solstice it is 89.8 days and back to the March Equinox is 89.0 days.