Astronomers Discover “Mini-Moon” Temporarily Orbiting Earth

Published on February 28, 2020

Research specialists at the University of Arizona discovered a “mini-moon” temporarily orbiting Earth, the second-ever of its kind.

On Feb. 15, astronomers Teddy Pruyne and Kacper Wiezrchos stumbled upon the car-sized object during their nightly observations on the Catalina Sky Survey, a NASA-funded project based out of Tucson.

Within days, six other observatories across the globe watched the remarkable object and calculated its orbit. Scientists estimate the “mini-moon” first entered Earth’s gravitational pull 3 years ago. What they found was nothing like our moon. Below is a diagram generated by astronomer Tony Dunn that shows the object messily tangling around Earth. The white represents our moon’s orbit.

Mini-Moon 2020
Image Credit: Tony Dunn / Catalina Sky Survey

The word “mini” in relation to our moon would be a major understatement. Researchers calculated the object to be approximately 6 feet to 11 feet across. To put that in perspective, the moon has a radius of 2,158.8 miles, according to NASA

So what is this thing?

On Tuesday, an announcement was made by The Minor Planet Center, an international organization that studies small bodies in space, that stated, “no link to a known artificial object has been found,” implying the “mini-moon”  is most likely an asteroid rather than space debris.

While small asteroids in space are nothing new — present-day data shows over 1 million known asteroids — what makes 2020 CD3 so special is it’s the second asteroid known to orbit Earth. 

The first was also discovered by the Catalina Sky Survey back in 2006. And like the first-ever discovered “mini-moon,” this one also won’t stay for long. In fact, it’ll probably leave Earth’s orbit in a couple of weeks.

“Unfortunately, we are catching this one on its way back out,” said Bill Gray, the brains behind the software that helped pinpoint the object. “It’s getting fainter. Already, it’s faint enough that if the Catalina Sky Survey looked at it now, it wouldn’t see it.” 

According to scientists, “mini-moons” like 2020 CD3 have an extremely low chance of staying in Earth’s orbit. To remain alongside Earth, an object would need to configure perfectly with the moon, which means it is possible but extremely unlikely.

Despite its quick departure since being discovered, the “mini-moon” has inspired new hope within the Catalina Sky Project and observatories worldwide. More information about 2020 CD3 could be revealed as scientists continue to study it.

Sarah Kocur is a Staff Writer at Grit Daily. Based in Las Vegas, she is a writer, radio host, and music enthusiast. She also writes for

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