Meet 3753 Cruithne, the asteroid mistakenly dubbed Earth's "second moon"
In the 1980s, an amateur astronomer discovered a rather special near-Earth asteroid. A decade later, scientists officially call the object a "quasi-satellite" of Earth, or a "quasi-moon". What is this object and why is it not really the second satellite of our planet?
A horseshoe-shaped orbit
The Moon is the only satellite of the Earth, but another object could have competed with it: the near-Earth asteroid (3753) Cruithne. The latter was discovered on October 10, 1986 by amateur astronomer J. Duncan Waldron on a photograph from the Siding Spring Observatory (Australia). More than a decade later, astronomers called the object a quasi-satellite of Earth.
But why is (3753) Cruithne not a true satellite of our planet? In reality, the trajectory of the asteroid is not perfectly elliptical like those of the Moon and the artificial satellites that humans have placed in orbit around the Earth. Indeed, it is a question of an orbit in the shape of a horseshoe or bean.
Specifically, the asteroid has an orbital period lasting just under a year, roughly similar to the period Earth takes to orbit the Sun. Thus, (3753) Cruithne is a "companion" of the Earth , always in its wake without playing the role of satellite.
A possible training ground for astronauts
The asteroid is never observable with the naked eye from Earth and this is no coincidence. Indeed, it has a diameter of only five kilometers and is at a good distance: 12 million kilometers. Moreover, there is no risk of collision with our planet, especially since the difference in orbital period between the two stars means that the horseshoe-shaped ellipse of (3753) Cruithne tends to move away gradually. Nevertheless, the initial position of the ellipse returns every 385 years , and has done so for more than 100,000 years. The maximum rapprochement between the two objects occurred in 1902 and will occur again in 2292 and 2676.
As the media Discover Magazine explained in an article on December 1, 2022, some scientists believe that the asteroid could represent an ideal training ground for astronauts. This would allow them to practice landing on small objects, with a view to launching real exploration missions on the surface of asteroids.
It must be said that the prospect of exploring asteroids can open the door to exploitation. Let us quote the example of 16 Psyche , of great interest to NASA. This object having a diameter of 226 kilometers could in theory bring back one billion euros to each earthling . It must be said that the asteroid contains a core of iron, nickel and gold.
Source: websites