[When I was younger and fascinated by astronomy, there was a big debate about the origins of the Moon. At the time, as best I recall, the capture theory was the most popular, that the moon was wandering around and captured by the earth. But I see in recent years, the "more way out" theory that the Moon was formed by another planet smashing into the Earth is now the dominant paradigm. I don't have a problem with this. I suspect that more data has sealed the deal on this matter. This does however, raise many questions. It is fascinating. Remember too that we can die in an instant if a piece of rock big enough hits the Earth. Life is thus precarious, and our position here is something which we as a race need to monitor and think about. It all makes for a weird and nasty past and a fascinating future. Jan]
It turns out the moon is a little younger than scientists previously thought — about 85 million years younger, to be precise.
In a new study, researchers at the German Aerospace Center found out that, not only did the moon once have a massive, fiery magma ocean, but our rocky satellite also formed later than scientists previously expected.
Billions of years ago, a Mars-size protoplanet smashed into the young Earth and, amid the debris and cosmic rubble, a new rocky body formed — our moon. In this new work, the researchers reconstructed the timeline of the moon’s formation. While scientists have previously thought that this moon-forming collision happened 4.51 billion years ago, the new work pegged the moon’s birth at only 4.425 billion years ago.
To determine this 85-million-year error in the moon’s age, the team used mathematical models to calculate the composition of the moon over time. Based on the idea that the moon was host to a massive magma ocean, the researchers calculated how the minerals that formed as the magma cooled solidified changed over time. By following the timeline of the magma ocean, the scientists were able to trace their way back to the moon’s formation.
"By comparing the measured composition of the moon’s rocks with the predicted composition of the magma ocean from our model, we were able to trace the evolution of the ocean back to its starting point, the time at which the moon was formed," study co-author Sabrina Schwinger, a researcher at the German Aerospace Center, said in a statement.
These findings, which show that the moon formed 4.425 billion years ago (give or take 25 million years), agree with previous research that aligned the moon’s formation with the formation of Earth’s metallic core, according to the statement.
"This is the first time that the age of the moon can be directly linked to an event that occurred at the very end of the Earth’s formation, namely the formation of the core," Thorsten Kleine, a professor at the Institute of Planetology at the University of Münster in Germany, said in the same statement.
These findings were described in a new study published on July 10 in the journal Science Advances.