The right eye of the "Man on the Moon" may have been the result of a cosmic collision that occurred 3.8 billion years ago, a new study suggests.
Specifically, an asteroid roughly 150 miles (241.4 kilometers) across — the length of New Jersey — may have struck the moon and formed the mysterious structure known as the Imbrium Basin.
Gashes And Grooves
Seen as a dark patch in the northwestern part of the moon's face, the Imbrium Basin is about 750 miles (1,207 kilometers) across.
Professor Pete Schultz, a planetary scientist from Brown University, says their study suggests that the Imbrium Basin was created by an incredibly gigantic object that was large enough to be classified as a "protoplanet."
According to Schultz, past estimates, which were based solely on computer models, yielded a size estimate of only about 50 miles (80.4 kilometers) in diameter.
This mysterious basin is surrounded by gashes and grooves that are large enough to be seen even by small telescopes from Earth. These gashes and grooves were believed to have been formed by rocks that blasted out of the crater.
These features are called Imbrium Sculptures and emanate from the center like spokes on a wheel and are concentrated on the southeast side. This indicates that the impactor came from the northwest.
But aside from these features, there is another set of grooves with a different alignment. This set appears to have come from a region to the northwest or the trajectory where the supposed impactor came.
This has puzzled scientists for a long time.
But thanks to experiments conducted at the NASA Ames Research Center, Professor Schultz managed to show that these grooves and gashes were possibly formed by chunks of the impactor that shaved off on the first contact with the moon's surface.
The grooves allowed Schultz to analyze the impactor's size. He says the key point is that the grooves were not radial to the crater because they come from the region of first contact.
Together with David Crawford, Schultz worked on generating computer models that exhibit the same kind of phenomenon would happen at the massive scales of a lunar impact.
The research team used their understanding of how the grooves were formed to estimate the size of the object that struck the moon, arriving at about 150 miles, which is actually a low-end estimation.
"It's possible that it could have been as large as 300 kilometers," says Schultz.
Why The Findings Are Important
Schultz and his team's findings may help explain some of the puzzling geological features surrounding the Imbrium Basin. It may also suggest that based on the size of other basins on the moon, Mercury and Mars, the early billion years of the solar system were packed with asteroids the size of protoplanets.
In fact, the researchers estimated the possible impactors on the moon's other basins, namely the Moscoviense and Orientale basins. They found that the size of the impactors were 100 kilometers (62 miles) and 110 kilometers (68.4 miles) across respectively.
"The large basins we see on the Moon and elsewhere are the record of lost giants," added Schultz.
Details of the new study are published in the journal Nature.