Our moon has been slowly drifting away from Earth over the past 2.5 billion years

You wouldn't think that the moon is moving away from Earth when you look up at it. We are aware of that. Reflecting panels were installed on the moon. The moon is 3.8 cm away from the earth every year.

We end up with a collision between the Earth and moon around 1.5 billion years ago if we take the moon's current rate of recession into account. The current recession rate is not a good guide for the past because the moon was formed 4.5 billion years ago.

Along with other researchers from other universities, we have been trying to find out more about our solar system's past.

The perfect place to find the long-term history of our moon has been found. It isn't from studying the moon, but from reading signals in ancient layers of rock. The study was published in the National Academy of Sciences.

Between the layers, reading.

The gorges in the national park are 2.5 billion years old. The iron and silica-rich minerals that were deposited on the ocean floor are now found on the oldest parts of the Earth.

At Joffre Falls, there are layers of reddish-brown iron formation just under a meter thick that are alternated by darker, thinner horizon.

The softer type of rock is more vulnerable to erosion. There is a regular, smaller-scale variation found at the outcrops. There is a pattern of alternating white, reddish and blueish- gray layers on the rock surfaces.

The question of the origin of the different scales of recurring patterns in the ancient rock layers was raised in 1972. The patterns may be related to the Milankovitch cycles.

Climate change.

The Milankovitch cycles show how the orientation of the axis of the Earth affects the distribution of sunlight on Earth.

The Milankovitch cycles change every 400,000 years. Over time, these variations exert a strong control on our climate.

Extreme cold or warm periods are examples of the influence of Milankovitch climate forcing in the past.

The size of lakes has changed as a result of the climate change. They are the reason for low levels of oxygen in the deep ocean. Our own species has been influenced by Milankovitch cycles.

The signatures of the changes can be seen through the changes in the rocks.

Wobbles were recorded.

One of the Milankovitch cycles has a correlation with the distance between the Earth and the moon. The Earth's spin axis is influenced by the precessional motion of the planet. When the moon was close to Earth, the duration of this cycle would have been shorter.

This means that we can estimate the distance between the Earth and the moon if we can find Milankovitch cycles and then find a signal of the Earth's wobble.

Trendall's theory was supported by our previous research which showed that Milankovitch cycles may have been preserved in South Africa.

Around 2.5 billion years ago, the iron formations in Australia and South Africa were deposited in the same ocean. The Australian rocks have better exposed variations that allow us to study them better.

Our analysis of the Australian banded iron formation shows that the rocks have a number of scales that repeat at 10 and 85 cm intervals. When we combined the thicknesses with the rate at which the sediments were deposited, we found that they occur every 11,000 and 100,000 years.

The 11,000 cycle observed in the rocks may be related to the precession cycle, which has a shorter period than the current 21,000 years. The distance between the Earth and the moon was calculated using this signal.

The moon was about 1.5 times the diameter of the Earth. It would take 17 hours instead of the current 24 hours to complete a day.

Understanding the dynamics of the sun.

Models for the formation of our solar system have been provided by research in astronomy.

One of the only ways to get real data on the evolution of our solar system is through our study and some research by other people.

The solar system dynamics can be determined from small variations in ancient rocks. One data point doesn't give us a complete picture of the evolution of the Earth-moon system.

New modeling approaches and reliable data are needed to understand the evolution of the moon. Our research team is looking for the next set of rocks that can give us more information about the solar system's past.

More information: Margriet L. Lantink et al, Milankovitch cycles in banded iron formations constrain the Earth–Moon system 2.46 billion years ago, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2117146119 Journal information: Proceedings of the National Academy of Sciences

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