Chinese geologists believe that 1.3 billion years ago one year on planet Earth lasted for 540 days, 13-14 months with 42 days in each month. There were 15 hours in one day.
The astonishing figures are the result of a long study of fossilized remains of ancient blue-green algae. Blue-green algae, also known as cyanobacteriae, are one of the most ancient forms of life on the planet. These are primitive and highly tenacious microorganisms belonging to prokaryotes (they have no typical karyon and chromosomal apparatus). Like bacteria, blue-green algae have no membrane between the kernel and the rest of a cell. They are colored blue-green but sometimes various pigments make them pink or black.
Blue-green algae actively respond to the change of day and night. Under sunlight they grow vertically and become brighter. When they do not get enough light, these algae grow aflat and acquire a faded color. Therefore, the exterior view of algae can suggest what the change of day and night occured when the algae were living organisms.
The fossilized remains of blue-green algae studied by researchers were dug out at the bottom of Mountain Yanshan in the northern province of Tianjin, China. The studied algae are 1.3 billion years old, and they got from equatorial regions to the northern Chinese province thanks to the shift of tectonic plates.
Researchers collected a huge number of fossilizations near the mountain. The fossilized remains present an exact picture of the rhythm of the algae growth. The rhythm indicated that the speed of Earth’s rotation 1.3 billion years ago was not at all like the one that we have today.
Before the 20th century it was believed that the steady process of Earth’s rotation was not subject to any changes. However, after a close analysis of the solar, lunar and stellar observations it became clear that Earth’s rotation was gradually getting slower because of tidal friction. The Great Soviet Encyclopedia states that over the past 2,500 years a sidereal day becomes on average 0.0024 seconds longer every century.
There are also seasonal changes in the speed of Earth’s rotation caused by meteorological phenomena and lunar attraction. Researchers have also registered spasmodic changes in the speed of Earth’s rotation as a result of which the duration of a day either increases or reduces by several thousands of a second within 1-3 years. The most significant changes took place in 1864, 1876, 1898 and 1920, and the Great Soviet Encyclopedia says no reasons of these changes have been registered yet.
It was already in the 1950th that researchers first spoke about cyanobacteriae as a wonderful chronometer of ancient epochs. But at that time, the amount of blue-green algae that science possessed was not enough for systematic studies. So, the 500 stromatolites containing a great number of fossilized blue-green algae excavated in China are coming in handy.
Translated by Maria Gousseva