The moon is older than previously thought: how did this mistake happen?

The moon is old, very old, there is no question about that. But when exactly it was formed has largely been unclear until now, mostly due to the many conflicting dates that have been floating about. However, this seems to have been clarified recently.

Before answering this question, it is first important to know how it was formed. A cosmic crash was the trigger. The young Earth was rammed by the Mars-sized protoplanet Theia.

The protoplanet collision that hit the Earth way back in its prehistoric part catapulted large amounts of rock from the two celestial bodies into space. It was from this mess of rock that the moon was formed.

Photo Credit: YouTube @NASAAmes

However, this happened between 80 and 180 million years earlier than previously thought, according to an article by a trio of researchers from the USA, France, and Germany in the journal 'Nature'.

The new study's research team was led by Francis Nimmo of the University of California in Santa Cruz, and the researchers investigated how the moon, in particular its crust, developed in its early days.

“We are particularly interested in the phase when the distance between the Earth and the Moon was about one-third of today’s distance,” Nimmo said about the research according to SciTechDaily.

According to the new findings, the moon was formed about 4.51 billion years ago, which would put its formation immediately after the formation of the solar system. But how could this be possible?

Rock samples brought to Earth by the Apollo astronauts and several unmanned missions previously helped scientists date the moon's formation to roughly 4.35 billion years old based on the cooling of the lunar surface. This was therefore previously considered to be its age.

Doubts about the moon's age arose after the researchers found something strange, crystalline inclusions in the moon rock, also sometimes referred to as zircons, which were older than the previous date estimated thought to be the moon's age.

The scientists explained the answer to this puzzling question in 'Nature': after its formation, the crust of the moon melted several times due to an enormous amount of heat at the time that adjusted the moon's"geological clock". This is how the incorrect dating came about.

Pictured: Training center 'Luna' in Cologne, Germany

According to scientists, the Earth's tidal effect heated the moon again 4.35 billion years ago. This caused large amounts of magma to rise from the interior to the surface.

The age of most rock samples taken from the moon's surface reflects magma cooling 4.35 billion years ago. This is why the actual age of the moon and its formation could be a lot older.

“The strong volcanism likely reset the Moon’s geological clock,” explained study co-author Thorsten Kleine from the Max Planck Institute for Solar System Research in Göttingen.

Pictured: Training center 'Luna' in Cologne

Kleine added that “lunar rocks samples therefore don’t reveal their original age, but only when they were last strongly heated." The study's new findings could also help solve another lunar mystery.

There are some chemical differences between the moon and the Earth that have been puzzling scientists for some time. Compared to Earth's mantle, the moon has a lower concentration of siderophile elements according to Nimmo and his team.

Siderophile elements are elements with a high affinity for iron and other metals. The second melting of the lunar mantle could explain why these elements have sunk more into the moon's core. Who knows how many other secrets the moon still hides?

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Photo Credit: Wiki Commons By OptoMechEngineer, Own Work, CC BY-SA 4.0