Now that Autumn is upon us, let’s look at some dates :
Meteorological Autumn
The meteorological autumn begins on 1st September 2018 and ends on 31st November 2018.
The meteorological seasons consists of splitting the seasons into four periods made up of three months each. These seasons are split to coincide with our Gregorian calendar making it easier for meteorological observing and forecasting to compare seasonal and monthly statistics. By the meteorological calendar, spring starts on 1 March.
The seasons are defined as Spring (March, April, May), Summer (June, July, August), Autumn (September, October, November) and Winter (December, January, February).
Astronomical autumn
This year the astronomical autumn begins on 24th September 2018 and ends on 21st December 2018.
The astronomical calendar determines the seasons due to the 23.5° tilt of the Earth’s rotational axis in relation to its orbit around the sun. Both equinoxes and solstices are related to the Earth’s orbit around the sun.
Solstices and equinoxes are considered to be the astronomical transition points between the seasons and mark key stages in the astronomical cycle of the earth. In a year there are two equinoxes (spring and autumn) and two solstices (summer and winter). The dates of the equinoxes and solstices aren’t fixed due to the Earth’s elliptical orbit of the sun. The Earth’s orbit around the sun means that in early January, the sun is closest (known as perihelion) and in early July it is most distant (aphelion).