Photoperiod
The photoperiod is the rhythmic alternation of light and dark caused by the rotation of the earth in conjunction with the inclination of the ecliptic (seasonal phase shift). This creates an increasingly pronounced seasonal dynamic north and south of the equator towards the poles.
Due to the gravitational pull of the moon and the associated tidal friction , the rotation of the earth is continuously slowed down and thus also the photoperiod is influenced. This effect extends the days of each year by around 16 microseconds . In the middle Jurassic 160 million years ago (at the time of the dinosaurs) - i.e. about 3.8 billion days ago - the year still had 385 days and not just 365 as it is today.As a result, a day lasted only 23 of our current hours, since the length of the Year, which is determined by the speed at which the earth moves around the sun, then as now is 8,760 hours. At the time of the dinosaurs, the photoperiod was on average a little shorter than it is today.
When the ancestors of plants began to colonize the country (around 400 million years ago), the year probably still had 405 days, i.e. a day had about 21.5 hours.
The photoperiod plays a major role in metabolic processes in living organisms .