The Earth had a near miss with an asteroid that left a 14-mile wide crater on the Moon – with the impact creating a “weird quasi moon” that was discovered in 2016, scientists belive.
Space rock 2016 HJ03 – also known as Kamo’oalewa – is very different to other asteroids that are close to Earth, as they usually hail from the main asteroid belt locked between Mars and Jupiter. Scientists now think Kamo’oalewa came from the Giordano Bruno crater on our Moon – after it was pummeled by an even bigger asteroid.
The finding marks the first instance of an asteroid being traced back precisely to its place of origin. The research, published in the journal Nature Astronomy, suggests that Kamo’oalewa has been orbiting the sun similarly to Earth for millions of years.
Chosen as the target for China’s Tianwen-2 mission, Kamo’oalewa measures between 150 and 190 feet in diameter, roughly half the size of the iconic London Eye Ferris wheel. It is described by Space.com as Earth’s weird ‘quasi-moon’ and scientists say it was likely thrown into space an asteroid impact on the Moon between 1 million and 10 million years ago.
Lead study author Yifei Jiao of the University of Arizona Lunar and Planetary Laboratory claims this is the first time a potentially hazardous near-Earth asteroid has been linked to a specific lunar crater. To unravel this space mystery, researchers implemented impact and dynamical modelling.
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The simulations suggested that launching a fragment as significant as Kamo’oalewa would require an impactor at least 1 kilometre in diameter to overcome the gravitational pull of the moon.
While the lunar surface is riddled with thousands of craters from impacts spanning the moon’s 4.5 billion-year history, only Giordano Bruno, with its 14-mile diameter and estimated 4 million years of age, fits the bill in terms of size and age, making it the most probable source of Kamo’oalewa’s origin.
Erik Asphaug, co-author and Lunar and Planetary Laboratory professor, says: “This was a surprise, and many were sceptical that it could come from the moon.”
“For 50 years we have been studying rocks collected by astronauts on the surface of the moon, as well as hundreds of small lunar meteorites that were ejected randomly by asteroid impacts from all over the moon that ended up on Earth. Kamo’oalewa is kind of a missing link that connects the two.”
According to Asphaug, the model provides more than just an explanation for the origin story of one particular asteroid. How massive rocks can be ejected from the surface of a planet and survive intact can be informative for fundamental questions, such as the origin of life in the universe.
One such theory, known as panspermia, suggests that life or its ingredients could have been brought to planetary bodies from other sources across space, in the form of “organic hitchhikers” coming along for the ride, Asphaug explained.
“While Kamo’oalewa comes from a lifeless planet, it demonstrates how rocks ejected from Mars could carry life at least in principle,” he said.
