Mysterious Earliest start to summer for over 200 years
Summer is starting earlier this year than it has for 228 years. At least astronomically speaking. On Thursday at 10.50 pm, the sun will reach the northernmost point of its annual orbit, heralding the start of summer.
20.06.2024, 14:56
SDA
The last time this happened earlier in the year was in 1796. Back then, the sun reached its northernmost point at 7.43 pm.
The astronomical start of summer is determined by the summer solstice. This is the time when the sun is parallel over the Tropic of Cancer. This is usually the case on June 21 or 22. The fact that the summer solstice falls on June 20 is a rare event. Between 1796 and 2024, this happened just twice: in 1896 and 2020.
Inaccurate calendar
The reason for this: an inaccurate calendar. This does not exactly match the Earth's orbit. One year corresponds to the time it takes the Earth to orbit the sun once. The problem is that the Earth does not need exactly 365 days to do this, but 365 days, 5 hours, 48 minutes and 56 seconds.
To compensate for this time, a leap day is inserted every four years. This also shifts the start of summer one day forward. However, this is around 45 minutes too much. As a result, the astronomical start of summer shifts forward by around three quarters of an hour every four years.
This occurs until the point in time when a leap year is omitted due to special calendar rules and the entire compensation for four years no longer applies. The next time this happens will be in the year 2100. The calendar will then be reset again and summer will no longer begin on June 20 for some years, even in leap years.
