This tiny space rock is a piece of our own moon


Asteroid Kamo’oalewa has no exotic origin: it is a piece of moon. Astronomers can even pinpoint an area where this space rock once lay peacefully in the soil.

The asteroid Kamo’oalewa was already discovered in 2016. It is a quasi-satellite of the Earth, namely an asteroid that orbits the sun at the same time as our planet. This makes it appear from the Earth’s surface as if Kamo’oalewa orbits our planet, while in reality it does not. The space rock has a diameter of 40 to 100 meters and rotates very quickly on its axis.

But where does Kamo’oalewa come from? In 2021, scientists discovered that the asteroid may have been a moon rock. To determine its exact origin, a team of astronomers developed a computer model to simulate a collision on the moon that could create an object like Kamo’oalewa. A number of surprising points emerged from this. For example, Kamo’oalewa is not old and its chemical composition is consistent with lunar material collected from the Giordano Bruno crater. Not only that: Kamo’oalewa and the moon sample from Giordano Bruno both also contain the mineral pyroxene.

NASA keeps a close eye on potentially dangerous asteroids. Near-Earth objects are asteroids and comets that come closer than 45 million kilometers to Earth at any given time. This makes them a threat to our planet. The smallest near-Earth objects are only a few meters in size, while the largest – 1036 Ganymede and 433 Eros – have a diameter of 35 and 17 kilometers!.

Scientists therefore suspect that the asteroid was born when a large meteorite crashed into the moon’s surface around four million years ago, forming the 22-kilometer-wide Giordano Bruno crater. This also explains the current position of the object.

By Giordano Bruno-krater. Photo: NASA

Are you curious about the Giordano Bruno crater? This crater is difficult to see from Earth, as we always see the same side of the moon. From this perspective, the crater lies on the border of the “front” and the “back” and is therefore occasionally visible when the moon makes a rocking motion. This is what astronomers call libration.

There is not yet one hundred percent certainty that Kamo’oalewa is really a piece of the moon, but the astronomers are quite sure of their case. Researchers may be able to find more evidence that Kamo’oalewa is a piece of the moon in future studies. This will undoubtedly be continued!