Pinch, punch – it’s the first of the month, and September is in full swing.
After an August that had some wondering if summer had come to a premature end, the ninth month of the year is the one which most associate with the start of autumn.
But does the start of September definitively mean the dawn of a new season?
We take a look at when the ‘real’ start of autumn is, and how it’s calculated.
When does autumn 2021 start?
There are two different dates that mark the beginning of autumn. One is the astronomical autumn date, measured by the earth’s orbit around the sun, while the other is meteorological autumn.
The latter was decided by splitting the Gregorian calendar into the four seasons we know as spring, summer, autumn, and winter.
The astronomical calendar determines the seasons due to the 23.5-degree tilt of the Earth’s axis in relation to its orbit around the Sun.
Using this method, autumn begins this year on 22 September 2021 and ends on 21 December 2021, when it gives way to winter.
The Autumn equinox is another way of referring to the start of the season because it is when the earth’s surface experiences 12 hours of daylight and 12 hours of darkness across one day.
Spring also has its own equinox based on the earth’s axis and sun rotation, which marks the start of the season, while the Winter and Summer solstices work in a similar way.
However, if you’re going by the meteorological system, then the start of autumn always falls on 1 September and ends on 30 November.
Winter then runs from December 1 to February 28, spring from March 1 to May 31 and summer from June 1 to August 31.
The seasons are split in this way so that they fit comfortably into the Gregorian calendar and make it easier for observing and comparing seasonal statistics.
So in other words, you either have another three weeks of summer to go, or it’s all over for another year – depending on which you follow.
Credit: Original article published here.