Monday November 25, 2024 at hours 5.43pm Italians the Earth will lose its “mini-moon”, an asteroid called 2024 PT5discovered on August 7, 2024 at a distance of 568,000 km from Earth, which on September 29 was temporarily “captured” by Earth’s gravity, becoming a sort of large “second moon” between 8 and 19 metres and distant currently 3.7 million km (about 10 times the Earth-Moon distance). Recent observations made with the Gran Telescopio Canarias (the largest in the world with a 10.4 meter mirror) suggest that 2024 PT5 it could be a small fragment of the Moonperhaps expelled following an ancient impact.
Why does the Earth have a second “mini-moon” and for how long
In reality, talking about “moon” or “mini-moon” for 2024 PT5 is slightly inappropriate, because the small celestial body it did not go into orbit around the Earth, but gravitationally it is behaving as if it were, because its speed is not enough to overcome the gravity of our planet.
In technical jargon, it is said that in the 56 days of “mini-moon” between September and November the asteroid 2024 negative geocentric energy. On November 25, geocentric energy will stop being negative, ending the period in which the celestial body will be “captured” by Earth’s gravity. Compared to Earth, the trajectory of 2024 PT5 in these two months resembles a horseshoe (as you can see in the animation that accompanies this article), having failed to complete a complete revolution around the Earth.
According to astronomers’ calculations, then, the January 9, 2025 the asteroid will effect another “close” passage with the Earth (however a 1.8 million km distance, almost 5 times the Earth-Moon distance). The next time 2025 PT5 comes back to visit us will be far away 2055.
What Earth’s “second moon” could be: the new study on 2024 PT5
A team of astronomers from the University of Madrid led by Marcos de la Fuente recently published on the portal arXiv (which collects scientific papers not yet peer-reviewed) an analysis of 2024 PT5 conducted through observations with the Gran Telescopio Canarias combined with computer simulations.
According to the results of the study, the celestial body is definitely natural (any hypothesis linked to space junk is therefore excluded) and it could be a real asteroid (i.e. essentially a “remnant” of the formation of the Solar System) but also a fragment of breccia coming from one of the lunar seasthat is, the expanses of basaltic material originating from the ancient volcanic activity of our satellite.
In short, the “second moon” of the Earth it could be a piece of our Moon!
Why asteroids like 2024 PT5 matter
2024 PT5 is a so-called asteroid Arjunathat is, with an orbit very similar to that of the Earth in terms of distance from the Sun, inclination and eccentricity (i.e. the “flattening” of the orbit). In particular, the distance of 2024 PT5 from our star varies by a maximum of 1% compared to the Earth-Sun distance, and the asteroid orbits the Sun in 372 days (just 2% more than Earth’s 365 days).
These celestial bodies are therefore to keep an eye on because their proximity to Earth’s orbit potentially puts them at risk of impacts with our planet. These asteroids are also important as ideal targets for future missions aimed at acquiring the know-how necessary to practice themining on these celestial bodies.
The mining of asteroids will in fact be one of the key sectors of the global space economy, given the quantity of raw materials that can be extracted without the disadvantages of mining on Earth.
