Switzerland’s longest day of the year is here. Travelling at 110,000 km/h, the earth completes a circuit of the sun every 365 days, 5 hours, 48 minutes, and 46 seconds, something called a tropical year. The longest day occurs in each hemisphere, when it reaches the point in this annual journey where it is most inclined towards the sun. In Switzerland this year that day is 21 June 2017.
The June solstice occurs anytime between June 20 and June 22. This variation is because a calendar year doesn’t quite equal a tropical year.
06:24 CEST this morning marked this year’s solstice, when the sun’s zenith is at its furthest point from the equator. On the June solstice, the North Pole tilts towards the sun and the sun shines directly over the Tropic of Cancer.
Switzerland’s longest day lasts close to 16 hours. According to timeanddate.com, in Zurich the day will last 15 hours and 57 minutes, starting at 5:29am and ending at 21:26. If you’re in Geneva, the day will be slightly shorter (15 hours and 43 minutes), starting at 5:43 and ending at 21:30. Because Geneva is nearly 2.4 degrees further westward (6.1432° vs 8.5417°) its sunrise is 14 minutes behind Zurich’s. It is also further south, shortening its day compared to Zurich.
At 47.3769 degrees of latitude, Zurich is nearly 1 degree further north than Geneva (46.2044 degrees), which adds around 10 minutes to the length of its longest day.
This year the longest day has come with some of the year’s hottest weather. The temperature reached 34 at 15:10 in Sion in Valais, according to Meteo Swiss. Thursday looks like it will be even hotter.