Astronomical autumn formally began with the autumn equinox early on Wednesday (September 23).
According to Royal Museums Greenwich, the equinox took place at 1.06am UK time on Wednesday, which was 6.06am in Bangladesh.
An equinox is the moment when the sun sits directly over the Earth’s middle, the equator. At that moment no part of the Earth is tilted towards or away from the sun, so the length of day and night becomes roughly equal all over the world. The event is called the autumn equinox.
In Britain people gather at historic sites such as Stonehenge to watch the sunrise on this special day.
For Bangladesh, however, the matter is a little different. Autumn does not begin afresh in Bangladesh on September 23; under the Bengali cycle of seasons, sharat is already under way.
The term autumn equinox belongs essentially to the astronomical seasons of the northern hemisphere. In Europe and many other countries of the northern hemisphere, this day is counted astronomically as the start of autumn.
The Latin word equinox means equal night, and in principle day and night should each last 12 hours. But because the atmosphere refracts light, some daylight remains for a while after the sun has set. As a result, the moment when day and night are exactly equal comes a few days after the equinox; it is known as the equilux, or equal light.
বাংলায় মূল প্রতিবেদন পড়ুন · Read the original Bengali report