The Moon may have undergone a kind of “volcanic rejuvenation” that has hidden its true age. According to new estimates, our natural satellite is 100 million years older than previously estimated. This conclusion was reached by scientists from different fields who decided to clarify its age. Scientists have found arguments in favor of the fact that the Moon is older than believed. For example, rare lunar zircon minerals indicate that our satellite may be about 4.45 billion years old, not 4.35 billion as previously thought.
How did the moon form?
In the late 1980s, scientists proposed the hypothesis that a Mars-sized object collided with the early Earth. The ejected molten material formed a separate celestial body that is now known as the Moon. This theory explains several key features:
- The Moon has few volatile substances such as water because its formation occurred in a molten state.
- The Moon has a small iron core because it was formed mostly from the outer layers of the Earth, which are iron-poor.
- Its white crust was formed from minerals that floated to the surface during solidification.
At first, the Moon was very close to Earth. It is about the orbital distance of today’s television satellites. The Moon’s proximity caused giant tides on the Earth’s molten surface. Gradually, the Moon began to move away and slow both its rotation and that of the Earth. Even now, the Moon is moving away from the Earth by a few centimeters per year.
How was the age of the Moon determined?
Investigating the age of the Moon is a challenging task. Thanks to the Apollo missions, scientists have samples of lunar rocks. The oldest of these are about 4.35 billion years old, which is 200 million years later than the formation of the Solar System.
Most geochemists assumed that this was the age of the Moon. However, for planetologists such as Alessandro Morbidelli, this contradicted models that suggested planets had formed much earlier. The hypothesis of such a late impact creating the Moon seemed unlikely.
In 2016, it was suggested that the Moon experienced extreme heating due to tides during its distance from Earth. A similar process is observed on Jupiter’s volcanic satellite Io. The stretching and compression of the satellite’s shape causes heating of its interior, which may have affected lunar rocks as well.
During this heating, the “clocks” in the rocks, which record age by radioactive elements, “rewrote” time. This means that the 4.35 billion-year-old rocks found do not record the formation of the Moon, but the period of its cooling after heating. Consequently, the Moon could have formed much earlier.
Where to find new evidence?
To test the new hypothesis, new samples of lunar rocks are needed. China’s “Chang’e-6” mission delivered materials from the dark side of the Moon in June 2024. If they indicate a similar age of rocks – 4.35 billion years. It will support the theory of the older age of the Moon. Otherwise, new explanations will have to be developed.
We previously reported on where the Moon was 2.5 billion years ago.
Provided by Space
