1. The beginning of autumn
We can say that autumn begins with two different dates. Autumn, determined by the Earth's orbit around the Sun, begins on the day of the equinox, which falls on September 22 or 23. Meteorological autumn always begins on September 1.

2. Trees are preparing for winter
One of the most amazing signs of autumn is the coloring of tree leaves in bright colors. Shorter days are a sign that trees should start preparing for winter. There is not enough light for photosynthesis in winter, so as the days of autumn shorten, trees begin to shut down their food production systems and reduce the amount of chlorophyll in their leaves.

3. Color chemistry
Chlorophyll is a chemical that makes the leaves of trees green, and as they decrease, other chemicals become more noticeable in the leaves.
They are responsible for the bright amber, red and yellow colors of autumn. The responsible chemicals are the types of flavonoids, carotenoids and anthocyanins.

4. The days are getting shorter
We often notice that the nights after the autumnal equinox become longer than the days, until this changes during the vernal equinox.

5. The Return of Persephone
In Greek mythology, autumn began when Persephone was abducted by Hades to become the Queen of the Underworld. In desperation, Persephone's mother, Demeter (the goddess of harvest), caused the destruction of all crops on Earth until her daughter was allowed to return, celebrating spring.

Stanislava