Asteroid impacts on the moon millions of years ago correspond with large space rock strikes here on Earth — including the massive impact that wiped out the nonavian dinosaurs.
The finding reveals that major impacts during Earth's prehistory were not isolated events. Instead, these asteroid strikes were accompanied by a series of smaller hits both here and on the moon, whose surface is littered with over 9,000 craters left by space rock impacts.
The research could help astronomers better understand the dynamics of the inner solar system and assist in calculating the likelihood that our planet will be struck by potentially devastating massive space rocks in the future.
Related: The hunt for asteroid impacts on the moon heats up with new observatory
Scientists from Curtin University's Space Science and Technology Centre (SSTC) in Australia obtained the results by studying microscopic glass beads within lunar soil samples returned to Earth by China's Chang'e-5 lunar mission in 2020.
These tiny glass beads were created by the intense heat and pressure generated by meteor strikes. This means researchers can reconstruct a timeline of lunar bombardment by assessing the ages of these beads.
While doing this, the SSTC team found that both the timing and the frequency of the asteroid impacts on the moon were mirrored by space rock strikes on Earth, meaning the timeline the team built could also provide insight into the evolution of our planet.
"We combined a wide range of microscopic analytical techniques, numerical modeling and geological surveys to determine how these microscopic glass beads from the moon were formed and when," lead study author Alexander Nemchin, a professor at SSTC, said in a statement.
The ages of some of the lunar glass beads indicated they were created around 66 million years ago, around the time the dinosaur-killing asteroid, known as the Chicxulub impactor, struck Earth in what is now the Gulf of Mexico, near Mexico's Yucatán Peninsula.
The impact led to what is known as the Cretaceous-Paleogene extinction event, which ultimately killed three-quarters of all life on Earth, including the nonavian dinosaurs.
The roughly 6.2-mile-wide (10 kilometers) Chicxulub impactor struck Earth at around 12 miles per second (19.3 kilometers per second), or 43,200 mph (69,524 kph), leaving an impact crater measuring about 93 miles (150 km) wide and 12 miles (19 km) deep. Aside from the shock waves generated by the initial impact, the asteroid hit caused a series of life-altering knock-on effects, including throwing up thick clouds of dust that blocked out the sun.
The new research from SSTC joins other work suggesting that this monster dinosaur-killing space rock may have been joined by other, smaller asteroids that also struck Earth and that could be revealed by studying the moon's history of asteroid impacts.
"The study also found that large impact events on Earth, such as the Chicxulub crater 66 million years ago, could have been accompanied by a number of smaller impacts," Nemchin said. "If this is correct, it suggests that the age-frequency distributions of impacts on the moon might provide valuable information about the impacts on the Earth or inner solar system."
The team now aims to compare data collected from the Chang'e-5 lunar soil samples with other soil samples from the moon and with the ages of craters across the lunar surface. This analysis could reveal other impact events across the moon and, in turn, help to uncover signs of asteroid impacts here on Earth that may have affected life.
The research was published Wednesday (Sept. 28) in the journal Science Advances.
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