The moon may be 40 million years older than previously thought – study
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A new study has shown that the Earth’s satellite, the Moon, may be 40 million years older than previously thought.
This is reported by Science Alert.
The Moon is thought to have formed shortly after Earth, about 4.4 billion years ago, when the Solar System was young.
That’s when, according to the theory, an object the size of Mars crashed into the Earth, which was still warm, soft and recently formed. The collision led to the fact that the substances of the Earth and the object that crashed into it were thrown into the surrounding space, and the Moon was formed from it.
| Apollo 17 astronaut Harrison Schmitt collects lunar samples. Photo: NASA |
However, a team of American geologists led by Jennica Greer claims that the Moon may be 4.46 billion years old and is “just a hair” younger than Earth.
It is not known exactly how and when the Moon was formed, but the presence of some specific elements convincingly indicates its terrestrial origin.
The giant collision hypothesis is currently the most popular. However, estimates differ as to when this giant impact took place.
However, a growing body of evidence based on the dating of lunar samples suggests that this occurred much earlier than 4.4 billion years ago. Some analyzes even suggest that the Moon formed 4.51 billion years ago.
Zircon crystals are a great way to track the age of a specimen. When they form, they contain uranium, but strongly reject lead.
Over time, the radioactive uranium in zircon decays into lead at a very well understood rate. Scientists can look at the ratio of uranium to lead in a zircon crystal and determine with high precision how long ago the zircon formed.
Such microscopic crystals can be found in samples of lunar dirt.
Greer and her colleagues studied zircon found in samples from the Apollo 17 spacecraft, the last lunar mission in 1972.
The team says these crystals must have formed after solidification of the moon’s surface from the molten world ocean that covered it immediately after its formation.
“When the surface was molten in this way, zircon crystals could not have formed and survived. So any crystals on the surface of the Moon must have formed after this ocean of lunar magma had cooled. Otherwise, they would have been molten, and their chemical signatures would have been would be erased”, – says Huck.
The study showed that the age of these particular crystals was 4.46 billion years. This means that the Moon must be at least the same age.
“Crystal samples from which the Moon was formed are the oldest known solids that formed after a giant impact,” says cosmochemist Philip Heck of the Field Museum and the University of Chicago.
This information could help scientists determine other aspects of the moon’s history, such as how long it took to form and solidify, and better estimate the date of the giant impact.
“It’s amazing to have evidence that the rock you’re holding is the oldest fragment of the Moon we’ve found. It’s a fulcrum for many questions about Earth.” Greer says.
Read also: Scientists named the probable reason for the formation of ice on the moon
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