The Moon was closer to us and it is still gradually moving away
Since the Apollo missions of 1969, NASA has installed reflective panels on the Moon. This is how they found that this moves 3.8 centimeters per year away from Earth. If we project this distance in time, the collision between the Moon and the Earth would have happened 1.5 billion years ago. However, the current model suggests that the Moon was formed about 4.5 billion years ago.
Researchers from Utrecht University and the University of Geneva have found a way to solve the riddle by interpreting signals from ancient rocks on Earth. As a reminder, the distance between the Moon and the Earth is directly linked to the Milankovitch cycle.
This explains the effect of periodic changes in the shape of the Earth’s orbit as well as the orientation of its axis, impacting on the climate on its surface.
The day lasted approximately 17 hours
Currently, this cycle lasts 21,000 yearsbut research suggests that this period was shorter when the Moon was closer to us. In order to detect the traces of these periodic weather changes, researchers study ancient sediments. For the experiment, they searched for a sign of the Earth’s oscillation to establish its period.
Sedimentary rocks have been found to exhibit scales of climatic variations from 10 to 85 centimeters. By analysing the speed with which these were depositedthe researchers established that these variations occur every 11,000 years and 100,000 years. Thus, it was deduced that the Moon was located at approximately 60,000 kilometers from Earth, 2.46 billion years ago. This implies that at this time, the day lasted approximately 17 hours instead of the current 24 hours.
What if we read the history of the universe in the rocks?
This research indicates that the history of Milankovitch cycles could be preserved in an ancient iron formation in South Africa. There will also be another potential site in Australia.
These deposits of old sediments of 2.5 billion years old located in the Karijini gorges are arranged in rhythmic layers composed of iron and silica. Those are alternate outcrops iron formations and darker, thinner sediments. Geologist AF Trendall suggested in 1972 that these patterns might be linked to climatic variations induced by “The Milankovitch Cycles”.
In short, the cycle greatly influences sun exposure and the climate of our planet over long periods. The extreme periods of cold or heat that have marked its past are a good illustration of this. Moreover, it helps to explain the periodic greening of the Sahara as well as the migration and evolution of species, including ours. Thus, sedimentary rocks, witnesses of these cyclical modifications, allow us to read the stages of these changes.