companion

The Earth does not travel alone around the sun. And not only because of the Moon, which logically always accompanies it, orbiting around it. It also has several traveling companions: objects, called co-orbitals, that take exactly the same time as our planet to make a complete revolution around the star. These objects are well known, but their origin is quite mysterious. There are astronomers who bet that they escaped from the asteroid belt. However, their silicate content suggests that they could be fragments of the Moon that jumped from its surface after the impact of a meteorite. Now, a team of scientists has assigned probabilities to each option, although for definitive proof of its origin we will have to wait a little longer. (469219) Kamo’oalewa. This is the name of one of the best-known coorbitals on Earth. It measures between 24 and 107 meters in diameter and the spectral analyzes that have been able to be carried out Telescopes such as the Large Binocular Telescope (LBT) and the Lowell Discovery Telescope (LDT) indicate that it is very rich in silicates, so it is likely that it comes from the Moon. In fact, the most accepted hypothesis so far indicates that it could have been formed during the impact that gave rise to the Giordano Bruno crater on our satellite. However, this new study, published in the journal Icarus, suggests that it is more likely that it is an asteroid escaped of the belt between Mars and Jupiter. Very unlikely. For an asteroid or a piece of the Moon to become co-orbital, they must not only escape from their place. Also They must have enough energy to be located in what is known as a quasi-satellite orbit. This, for a body the size of Kamo’oalewa, is highly unlikely. Quasi-what? A quasi-satellite has certain similarities with a satellite, but it is not the same. When we look at one of them from the planet it accompanies, in the direction of the Sun, it appears that it is in orbit around the planet, but in reality it rotates around the Sun itself. This, among other reasons, is due to the fact that is outside the Hill sphere of the planet. That is, the environment dominated by its gravity. Being outside of said orbit, it is influenced by the planet’s gravity, but above all, in this case, it is influenced by that of the Sun. Be that as it may, falling and staying in that orbit is complicated, as we have already seen and, above all, as these scientists have demonstrated. Win the asteroid option. These scientists have created models that simulate the trajectory of 12,000 synthetic particles launched from the lunar surface at different speeds and angles, following their orbits for millions of years. The goal was to see how many stabilized at co-orbital points with the Earth. In total they found 70 objects with a diameter greater than 10 meters capable of doing so. 70 out of 12,000! Now, when they repeated the procedure by swapping lunar particles for objects from the asteroid belt, they found more candidates. 1,600 in total. Tianwen-2 will return samples to answer the mystery in 2027 Tianwen-2 will have the key. The origin of coorbitals is so intriguing that China already has sent a ship to analyze the surface of one of them. Specifically from Kamo’oalewa himself. The Tianwen-2 mission left in May 2025 towards this object, with the aim of collecting at least 100 grams of samples and return them to Earth for analysis. It is already known that there are silicates, or at least it is suspected, but a deeper idea of ​​the composition is needed to understand the origin of this object. Orbit insertion is expected to occur next June if all goes well. Then he will spend a few months collecting samples to put them in a capsule, which will land back on Earth. already in 2027. Two options. If the analyzes of Tianwen-2 conclude that Kamo’oalewa came from the Moon, the lunar impact mechanics would have to be rethought, since it would be very rare for one of these fragments to have been able to reach its final location with what we know so far. On the other hand, if it is proven that it comes from an asteroid, it would be necessary to study where these silicates come from, since they are very unconventional for an object of these characteristics. Whatever is concluded, there will be a lot of fabric to cut, that is clear. ç Image | NASA |China News Service In Xataka | The Earth has moons that we don’t know about: exploring them is key to revealing the secrets of our solar system