Earth is known to have one constant companion as the Moon, for the past billions of years. It is though, not the only one as at times, a smaller object gets trapped in the gravitational pull of the Earth, temporarily orbiting it.?
We refer to such objects as ¡®mini-moons¡¯. And soon we will witness one ourselves!
Now scientists have discovered a mini-moon approaching Earth, set to come as close as around 43,000 km away. It is estimated that the object will orbit the Earth from October this year to May 2021, before leaving the Earth¡¯s orbit.
The highlight, however, is that this mini-moon seems to be human made. Named Asteroid 2020 SO, the space junk is being believed to be a 1960s booster rocket by Dr. Paul Chodas, the director of NASA's Center for Near Earth Object Studies.
In an interview with CNN, Chodas explains that the object is following ¡°precisely the kind of orbit¡± that a separated rocket stage used during earlier lunar missions would follow after its passes by the Moon. He mentions that ¡°it is unlikely that an asteroid could have evolved into an orbit like this, but not impossible.¡±
In simulations of the object shared on Twitter, the mini-moon will enter and leave the Earth's orbit through its two Lagrange points. Lagrange points are orbital points that have an equilibrium of the gravitational pull by two large co-orbiting bodies - in this case Sun and Earth -? on each other. Any object in such points will maintain its position between the two orbiting bodies.
Space archaeologist Alice Gorman of Flinders University in Australia mentions that the velocity of the object is much lower than the velocity of an Apollo asteroid - asteroids that cross Earth's orbit. It has been reported to be 0.6 km/sec.
In an interaction with ScienceAlert, Gorman said "What I'm seeing is that it's just moving too slowly, which reflects its initial velocity. That's essentially a big giveaway."
Once suspicions arose that the incoming object is a space junk, Chodas tried to trace its origins. He ¡°tentatively identified¡± the supposed mini-moon as the Centaur rocket body that delivered the Surveyor 2 experiment payload to the Moon. The rocket was launched back in September 1966.
If this is true, the object will not be a mini-moon at all and instead just be space junk. It is, however, interesting to see how it will yo-yo its way around Earth and be on its path soon after. The fact that it is human-made might also shed light on the question - ¡°just how much space junk is out there?¡±