We all know and love our moon. It has been Earth’s constant companion for billions of years, a mainstay of the sky. But he is not our only companion.

Every now and then, a smaller object is temporarily captured in the orbit of our planet, hanging around for a short period of time – a few months or years – before it is thrown back into space.

We call these creatures Minimoons, and while we made some tentative discoveries of these temporarily captured asteroids, only two have been confirmed – 2006 RH120, Which visited in 2006 and 2007, and 2020 CD3, in Earth’s orbit from 2018 to 2020.

Now astronomers have discovered a new object, called 2020 SO, on an incoming trajectory that it will likely see temporarily captured by Earth’s gravity. The forecast has an object that arrives next month, in October 2020, and stops until May 2021, when it leaves for the surrounding areas elsewhere.

As you can see in the simulation below, the object’s path indicates that it will enter and leave through two of the Lagrange points on Earth, which are fixed gravitational points created by the Earth’s gravitational interaction with the Sun.

Asteroid 2020 SO may be captured by Earth from October 2020 to May 2021. The current nominal path shows capture through L2, and escape through L1. Very messy path so be prepared for lots of reviews as new notes pop up. Embed a Tweet @MrCo0e https://t.co/h4JaG2rHEd pic.twitter.com/RfUaeLtEWq

– Tony Dunn (@ tony873004) 20 September 2020

This would be very noteworthy in and of itself – but there is a twist. The Earth-like orbit and the low velocity of the 2020 SO indicate that it is not actually an asteroid; Its properties are, according to experts, more consistent with something man-made.

2020 SO is classified as an Apollo asteroid In the JPL Small-Body database A class of asteroids whose paths cross Earth’s orbit. Often this class of asteroids has encounters near Earth. But there are some indications that the 2020 SO is not the same as others.

The object is located in an orbit with a height of just a smidge for a year, and an inclination very low relative to the Earth’s orbit; That is, it is not inclined, but on the same orbital path. Its eccentricity – the deviation of the shape of its orbit from a full circle – is slightly higher than that of the Earth’s orbit. Its speed is much less than that of the Apollo asteroid.

“The speed seems to be great,” space archaeologist Alice Gorman of Flinders University in Australia told ScienceAlert. “What I see is that it is moving very slowly, which reflects its initial velocity. This is basically a great gift.”

Objects from the moon have a slower velocity than asteroids, too. However, Gorman noted, 2020 SO is slower than moon rocks.

All this indicates that the object is potentially a space junk; specially, According to Paul Choudas of the Jet Propulsion LaboratoryNeglected Centaur stage A missile launched a test payload called Surveyor 2 to the Moon in September 1966.

asteroid # 2020SO It is suspected to be the booster for the Surveyor 2 Centaur missile, launched on September 20, 1966. Earth-like orbit and low relative velocity indicate a possible human-made object.

– Kevin Haider (@kpheider) September 21, 2020

Reusable rockets are only a recent invention, because they are technically very difficult to retrieve. The solution widely used for decades was to launch multi-stage rockets designed to collapse. The Reinforcement stage Returns to earth for reuse; The remainder of the rocket, which carries the payload, is thrown into space once its mission ends.

These neglected stages make up a lot of space junk. And according to Gorman, it is very easy to lose.

She said: “There are many factors in the space environment, such as gravitational factors and other things that affect movement, which may sometimes be highly unpredictable.”

“You have to keep tracking these things, or you can kind of easily overlook them. And if they do something a bit unpredictable, and you look in the wrong direction, you don’t know where it went. It’s amazing how many things are lost.”

The estimated size of the 2020 SO matches the characteristics of the Centaur stage of the 1960s era. to me NASA’s CNEOS database, Body length is between 6.4 and 14 meters (21 and 46 feet); A Centauri stage measures 12.68 meters (41.6 feet).

Asteroids are detected in the sky as bright, moving objects – a point in the dark. From this we can infer velocity and orbit, and estimate volume but it is impossible to determine shape or composition without more detailed observations.

2020 SO is slated to make two hits close to Earth. On December 1, 2020, it will pass approximately 50,000 kilometers (31,000 miles). On February 2, 2021, it will fly at 220,000 km.

Both are not close enough to enter Earth’s atmosphere – the body poses no danger whatsoever. But these distances, especially at slow speeds, may be sufficient to closely study them and ascertain what the 2020 SO is.

We might be able to give an approx. Spectroscopy can help determine if an object is coated. The amount of light it reflects can provide information to aid in planning long-range space missions. If 2020 SO was that stage from Centaur in 1966, it has been in space for 54 years – a man-made spacecraft that has held the void for all those decades.

“It would be interesting to do some reflection spectroscopy, which would show how rough the surfaces are, how susceptible they are to pitting and decay from being bombarded by fine dust and meteorites,” said Gorman.

“It’s human matter that is in a different part of space. So, it would be interesting to compare that to the results you get from things in low Earth orbit, which are much denser material.”

And of course, whether it is a missile stage or not, the characteristics of 2020 SO could help us identify other near-Earth creatures in the future. If it is man-made, that means that the next time we see an object with similar properties, we have very little information supporting a human origin.

If it’s an asteroid, that means we have a really strange rock on our hands that shows that asteroids can move – really unexpectedly – like rocket stages.

So whatever 2020 SO, we’ll have a lot to learn from our upcoming mysterious guest.