Kamo’oalewa: what the strange “mini moon” close to Earth looks like and why its origin is a mystery

For a few years, scientists have been wondering what is the origin of the asteroid Kamo`oalewa.

It was discovered in 2016 and astronomers know that it has a relatively close orbit to Earth, but not much else.

New research, however, has added new clues to its mysterious origin: it could be a fragment of our own Moon.

“It does not look like what we would have expected if it were just a ‘normal’ asteroid,” says Benjamin Sharkey, an astronomer at the University of Arizona (USA) and lead author of a new study published in Nature.

His Venezuelan colleague Juan Sánchez, who participated in the investigation, tells BBC Mundo: “Perhaps it could have been ejected due to a collision between the Moon and a meteorite. The material was possibly ejected from the surface of the Moon. “

Although the only way to know the nature of Kamo`oalewa is by obtaining samples, something that could happen this same decade, scientists have several elements to consider that his theory is correct.

But first, what is Kamo`oalewa like?

A “quasi satellite”

Kamo`oalewa (formerly known as 2016 HO3) was discovered in 2016 by the Pan-STARRS 1 telescope, which is located in Hawaii.

The scientists gave it a name in Hawaiian that can be translated into Spanish as “Swaying Heavenly Shard.”

It has an approximate length of 40 metersand technically it is considered a “Quasi satellite”, not a “moon”.

“A quasi-satellite of the Earth is an object that is in a co-orbital configuration with the Earth. As such, the object remains close to our planet as it orbits the Sun ”, explains to BBC Mundo Sánchez, who is a graduate of the Central University of Venezuela.

Unlike the Moon, the Kamo`oalewa It does not orbit the Earth, but the Sun, on a parallel path. That is why if our planet disappeared, this rock would follow its current orbit.

Scientists have so far detected five quasi-satellites, but have practically only been able to study Kamo`oalewa.

“It is easier to observe than the other quasi-satellites that are known. Once a year, during the month of April, this object becomes bright enough so that it can be observed with large telescopes from Earth, ”says Sánchez.

The others are less visible and could not be analyzed.

A very particular rock

When observing this asteroid, astronomers discovered that it was unusually red, an indication of the presence of metallic minerals.

“In simple terms, basically what we did was study how sunlight is reflected off the surface of this object to try to determine what it is made of. What we found is that the object is made of silicate minerals, ”says Sánchez.

“And what caught our attention is that this appearance is more like the surface of our Moon than other near-Earth asteroids that have been studied,” continues the physicist.

The scientists also inferred that the only known similar rock is a lunar sample brought in by the Apollo Missions in the 1970s.

“And this caught our attention, because it is the first time that we have tried something like this. And the fact that we have observed it in a quasi-satellite of the Earth, in an object that orbits around the Sun, very close to the Earth, makes us suspect that the object could have originated on the surface of the Moon ”, he points out. Sanchez.

Other hypotheses hold that Kamo`oalewa could be part of the so-called Near Earth Objects, or “Trojan asteroids”, which are not necessarily related to the Earth-Moon duo.

But the experts of the new study consider that the data thrown in their study “favors” their theory.

“We are not 100% sure and cannot rule out that the object was simply captured from the general population of near-Earth asteroids. The only way is to obtain samples of the object to be sure, ”says Sánchez.

And that might not be that difficult.

If China’s plans go ahead, this very decade Beijing to launch robotic mission to visit Kamo`oalewa and a comet to bring samples.

Then it could be confirmed if the Kamoʻoalewa is a part of our Moon.