Earth has an intriguing semi-satellite that could be a fragment of the Moon

Earth has a semi-satellite that constantly moves closer. Kamo’oalewa may be an ancient piece of the moon. An invention that brings a new perspective on these little-known stars.

There are a few thousand satellites orbiting the earth but only one natural, To the moon. Only by zooming in on the image can you find objects that appear to be approaching the planet and orbiting it. These were nicknamed semi-satellites, and one of them attracted the attention of a group of American researchers who published it. A study About this, in the journal Nature Communications Earth & Environment.

⁇ This is the asteroid Kamolova, University of Arizona senior writer Ben Sharkey tells Numeroma. We have seen that this is very different from known asteroids. In fact, it looks similar to the lunar models studied from the Apollo mission. ⁇

Kamo’oalewa is a semi-satellite

But before we go into the details of this study, what is the difference between a semi-satellite and a simple one? Asteroid ? Obviously, there is an elegant dash. A semi-satellite orbits the Sun, but at the same average longitude of the planet. This means that when you position yourself from the point of view of the planet, the object appears to be orbiting it, and visible at regular intervals. But contrary to its name, it is not the planet’s satellite orbiting it. Kamo’oalewa, discovered in 2016, is a regular subspecies that sometimes “only” passes 14 million kilometers away from us. It measures only a few ten meters and according to simulations its orbit seems stable for at least a few centuries.

Intriguing red reflections

If he is the one conspiring astronomers, he is, above all, easy to notice. It will be close to Earth for a very long time, unlike its allies. This prompted Ben Sharkey’s team to rotate two Arizona telescopes towards him, first to determine his color and rotation period in April 2017. Then refine the measurements in March 2021 and take some pictures near the infrared.

Some traits emerged in Ben Sharkey’s eyes: ” Kamo’oalewa reflects sunlight in the general pattern of minerals found on the moon, which is very rare in the most common asteroids. This, and its proximity to the Earth, suggests that it originated from the Moon. ⁇

At first everything seemed normal: silicate compound like ordinary asteroids, even with a similar rotation. But it was the infrared imaging that revealed these unusual red reflections. This color can be explained by three factors at this wavelength:

• Viewing angle. But here, taking into account the inaccuracies, a spectrum that draws more towards red is not explained.
• The presence of small grains of rock On the surface. They are small and appear to reflect red light. Again, even the smallest grains are not enough to illustrate this color.
• The presence of metal Shooter in red, but the only known asteroids that can access this are basically made of metal, not silicate, so it doesn’t work.

How to interpret this red color? There is one last criterion: the erosion of the moon. Studies show that it reduces the albedo of rocks and turns them red. What can be observed in the samples collected during the Apollo voyage. Eventually, researchers found rocks that closely resembled Kamolova in these specimens.

Serious lack of data

Another hypothesis is the Trojan asteroids. Not much is known about these stars, which will soon be studied by NASA’s Lucy study. But data on them is so sparse that it is difficult to confirm that idea. So the most possible is the lunar origin, which raises many questions, especially the asteroid formation. He may have been born in a giant collision on the moon, but when and under what circumstances? Mystery.

The main obstacle for researchers is the lack of data. Observations of Kamo’oalewa are rare, but observations of other known semi-satellites are still rare. So there is no relevant comparison, but the authors did not give up: ” We hope to have infrared images available soon, Says Ben Sharkey. At these wavelengths, there are very distinct tracks that stand alone, which can eliminate uncertainties.. ⁇

If the discovery is confirmed, it will resume research on the formation of the Earth-Moon pair. The story of this system is told in part by fragments of the moon falling to Earth in the form of meteors, but how the object moved from one star to another is not enough for us. ” Determining the event created by Kamo’oalewa will provide us with valuable information about the process, I promise to Ben Sharkey. Continuing to study it is to expect great discoveries. ⁇

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