We have discovered the origin of our second moon through scientific analysis

After three years of research, scientists have made significant progress in determining the origin of Kamo’oalewa, the intriguing quasi-moon believed to be a fragment of Earth’s Moon. In addition to demonstrating the rapid advancement in our understanding of the relatively new field of quasi-moons, this discovery pays tribute to a scientist who embraced the idea of multiple worlds.

Up until recently, the inner solar system was considered to be quite desolate, with only three moons orbiting four planets, along with a handful of asteroids that ventured closer than the main belt. As scientists search for objects that may pose a threat to Earth, they have also stumbled upon a fascinating discovery known as quasi-moons. These objects revolve around the sun in sync with the planets, resulting in their proximity for extended periods before transitioning into horseshoe-shaped orbits.

One of these celestial objects, a moon-like entity orbiting Venus, gained attention for its charming name, Zoozve.

Through our investigations, it has come to our attention that Earth possesses a small number of quasi-moons. All of them are small; some are as big as elephants. The largest we’ve discovered is Kamo’oalewa, measuring approximately 60 meters or 200 feet in length (if you prefer a more precise measurement). Kamo’oalewa, while not a true second moon, can be considered more towards the moon end of the asteroid-to-moon spectrum, making it a potential candidate for the title of quasi-satellite.

After being discovered five years ago, scientists finally analyzed Kamo’oalewa’s spectrum and made an intriguing observation. It closely resembled the spectrum of lunar rocks, but it was completely different from any known asteroid.

It is worth considering the possibility that Kamo’oalewa was dislodged from the Moon due to an asteroid collision. This theory gains support from the fact that Kamo’oalewa’s orbit is more stable than other quasi-moons and its velocity is significantly lower than that of the Earth-Moon system. These characteristics align with what one would expect from an object originating nearby. After carefully analyzing the necessary conditions, it was determined that creating an object like this is indeed feasible.

However, the Moon is dotted with numerous impact craters. Discovering the origin of Kamo’oalewa may appear to be a challenging task, but a recent study asserts that it has been accomplished.

Despite its modest size, Kamo’oalewa would have originated from a significantly larger crater, estimated to be around 10–20 kilometers (6–12 miles) in diameter, according to the calculations made by the authors. In addition, it’s probably quite young. The orbit of Kamo’oalewa, while relatively stable for a quasi-satellite, is not expected to endure for hundreds of millions of years due to the gravitational forces exerted by planets and the potential risk of colliding with another object.

The authors have narrowed down the possibilities to a short list, with the crater Giordano Bruno being considered the most likely candidate. With a width of 22 kilometers (14 miles) and an estimated age of 1 to 10 million years, this object is quite fascinating.

The spectrum collected from Kamo’oalewa closely resembles the samples obtained during the Apollo 14 mission, as well as those gathered by the Soviet Luna 24 lander and certain moon meteorites.

To ensure an accurate match, it would be advisable to conduct a more comprehensive analysis of Kamo’oalewa, potentially through an on-site investigation. Authors have raised suspicions about Giordano Bruno as a potential candidate for the youngest lunar crater of suitable size. However, there are other well-known craters, like Tycho, that could also be considered young enough.

If the authors’ hypothesis is correct, it is possible that several other objects of comparable size were expelled when a massive 1.6-kilometer (1-mile) wide object collided with the Moon, resulting in the formation of the Giordano Bruno crater. Many objects would have collided with the Earth or been expelled from the Solar System, but it is possible that there are still other survivors to be aware of.

“Space missions have yet to explore asteroids that are tens of meters in size, making them one of the least understood types of small bodies. Despite this, these asteroids pose the most frequent threat to Earth and could potentially provide valuable resources in space,” the authors explain. The upcoming Tianwen-2 mission to Kamo’oalewa in the following year has the potential to revolutionize our understanding of material evolution on and off the Moon.

Without any available samples of Giordano Bruno, it is not possible to determine its age with The lack of smaller craters on its surface, however, suggests that the steep walls and prominent surrounding rays indicate a relatively recent formationsurface. The crater gained attention when its formation was suggested as a possible explanation for the events recounted by medieval monks. However, this notion has since been widely discredited. The crater is named after a philosopher who was executed for heresy due to her proposition that the stars had planets of their own, although there may have been other motivations behind her execution.

The study has been published in Nature Astronomy.