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Say goodbye to Earth’s ‘second moon’, because it’ll be gone soon

In the weirdness and constant news cycle of 2020, you might have missed a bizarre piece of astronomy news: Researchers spotted an object, called 2020 SO, which appeared to be a second moon in orbit around our planet. Dubbed a “minimoon,” this object turned out to have a story all its own. But now it’s about to leave our planet’s orbit and head off into the blackness of space.

Object 2020 SO was first spotted in September 2020, when it came close to Earth. It was first thought to be an asteroid, but it was at a relatively low altitude — around half the distance between Earth and the (real, primary) moon. Debate ensued over what it was, with most astronomers deciding it was likely artificial in nature.

Observations of the object commenced, using tools like the Infrared Telescope Facility (IRTF), and eventually, NASA declared that the object was in fact a rocket booster from the 1960s. Researchers were able to match the composition of the object to a similar booster from the 1970s which was also in orbit.

On December 1, 2020, object 2020 SO made its closest approach to Earth, and since then it has been within Earth’s gravity. But now it is breaking free and heading into a new orbit around the sun. NASA created an animation to show the path that the object is taking:

The Looping Orbits of 2020 SO

The object will make its final close approach to Earth this week, on February 2, coming within 140,000 miles of the planet according to EarthSky. But by March it will have broken free of Earth’s gravity and be headed off on a new course in orbit around the sun instead.

If you’d like to see this visitor from another time and say goodbye before it leaves our planet for good, then the Virtual Telescope Project will be holding a “Farewell, mini moon” event on February 1. You can tune in to see a live feed of the object as it passes us by for the last time.

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