Astronomical Autumn vs. Meteorological Autumn

Autumn, a season loved by many, can be defined in two different ways: meteorological autumn and astronomical autumn. Let’s explore what these terms mean and how they determine the start of this colorful season.

Meteorological Autumn is a practical approach used by meteorologists and climatologists. It simplifies record-keeping and forecasting by dividing the year into neat calendar months. According to this definition, autumn encompasses the months of September, October, and November in the Northern Hemisphere, and March, April, and May in the Southern Hemisphere. It’s a time when we transition from the warmest to the coldest months of the year. It’s like nature’s way of preparing us for the chilly days ahead.

On the other hand, Astronomical Autumn takes a celestial perspective. It’s based on the tilt of the Earth’s axis as it orbits the Sun. Astronomical autumn is determined by a fascinating event called the equinox. In the Northern Hemisphere, autumn begins with the autumnal equinox, usually occurring around September 22nd or 23rd. During this magical moment, the Sun crosses the celestial equator, resulting in day and night being almost equal in length. In the Southern Hemisphere, the autumnal equinox takes place around March 20th or 21st, signaling the start of autumn in those parts of the world.

While meteorological autumn relies on calendar months, astronomical autumn is closely tied to celestial events like the equinox. The meteorological definition is practical for data analysis and forecasting, while the astronomical definition connects us to the wonders of the universe and our position in it.

It’s fascinating to see how different cultures have their unique ways of talking about seasons. When does the autumn start for you?