As adults we should know this right? We spent most of primary school being taught about how the earth orbits and what planets and stars are in our solar system, most of us had the opportunity to work on class projects and present our knowledge and facts to the class.
So when my nieces asked me this very question, why was I unable to explain it in such a simple way? My brief answer was ‘because the Earth is closest to the sun’
This really got on my last nerve, that I couldn’t explain it in depth so I’ve spent some time looking for the most appropriate answer to this question.
It all goes back to the angular way earth rotates and goes around the sun. As earth rotates around itself one or the other poles are pointed towards the sun. Our summer is the time when the north pole is pointed towards the sun. In our summer the days are hotter and longer. The opposite happens in the southern hemisphere. The south pole points away from the sun. The days are cold and shorter.
During our summer, the Northern Hemisphere leans toward the sun in its revolution, there are more daylight hours, and the sun’s angle is more perpendicular to us than at other times of year. The longer days and more concentrated sunlight results in more heating. (Shadows are shorter in the summer because the sun strikes Earth more directly.)
Earth doesn’t stay in one place! It orbits (or circles) the Sun, making an oval shape. One orbit takes one year. Because the Earth is tilted, one hemisphere will be closest to the Sun for part of the year. But as Earth continues orbiting the Sun, that tilt puts the other hemisphere closer to the Sun. In the Northern Hemisphere, the longest day of the year, called the summer solstice (SOAL-stiss), happens around June 21, because that’s when the North Pole is tilted closest to the Sun. The opposite happens around December 21: the South Pole is closest to the Sun, so the Northern Hemisphere has its shortest day of the year. Meanwhile, the Southern Hemisphere is having its own summer solstice.